In academic texts, writers frequently make reference to other studies and to the work of other authors. It is important that writers guide their readers through this literature.
One of the distinguishing features of academic writing is that it is informed by what is already known, what work has been done before, and/or what ideas and models have already been developed. Thus, in academic texts, writers frequently make reference to other studies and to the work of other authors. It is important that writers guide their readers through this literature. This article lists some of the phrases that writers may use for this purpose.
A note on the literature review: It is the purpose of the literature review section of a paper or dissertation to show the reader, in a systematic way, what is already known about the research topic as a whole, and to outline the key ideas and theories that help us to understand this. As well as being systematic, the review should be evaluative and critical of the studies or ideas which are relevant to the current work. For example, you may think a particular study did not investigate some important aspect of the area you are researching, that the author(s) failed to notice a weakness in their methods, or that their conclusion is not well-supported (refer to Being Critical).
A note on referencing style: The way a writer refers to other sources varies somewhat across different disciplines. In some cases, where the individual author is important, the author’s name will be the main subject of the sentence; in other cases, the author’s name may only be mentioned in brackets ( … ) or via a number notation system (e.g. footnotes and endnotes). The ‘author as subject’ style is less common in the empirical disciplines (sciences) and more commonly used in the humanities. Different referencing systems are used in different disciplines. In the majority of the examples given here, the Harvard in-text referencing system has been used.
A note on verb tenses: For general reference to the literature, the present perfect tense (have/has + verb participle) tends to be used. For reference to specific studies carried out in the past, the simple past tense is most commonly used. This is normally the case where a specific date or point in time in the past forms a part of the sentence. When referring to the words or ideas of writers, the present tense is often used if the ideas are still relevant, even if the author is no longer alive. The examples given below reflect these general patterns, but these are by no means rigid.
The literature on X has highlighted several …
Different theories exist in the literature regarding …
More recent attention has focused on the provision of …
There are relatively few historical studies in the area of …
A large and growing body of literature has investigated …
Much of the literature since the mid-1990s emphasises the …
Much of the current literature on X pays particular attention to …
There is a large volume of published studies describing the role of …
The existing literature on X is extensive and focuses particularly on …
There is a relatively small body of literature that is concerned with …
The generalisability of much published research on this issue is problematic.
A considerable amount of literature has been published on X. These studies …
The academic literature on X has revealed the emergence of several contrasting themes.
Previous research findings into X have been inconsistent and contradictory (Smith, 1996; …).
| (Much of) | the literature on X | comes from … acknowledges … takes as its focus … is concerned with … is exploratory in nature. lacks clarity regarding … pays particular attention to seems to have been based on … has emphasised the importance of … perpetuates out-of-date notions of … is extensive and focuses particularly on … |
Research into X has a long history.
For many years, this phenomenon was surprisingly neglected by …
Only in the past ten years have studies of X directly addressed how …
Prior to the work of Smith (1983), the role of X was largely unknown.
Over the past decade, most research in X has emphasized the use of …
In recent years, there has been an increasing amount of literature on …
Early examples of research into X include … (Smith, 1962; Jones, 1974).
During the past 30 years, much more information has become available on …
The first serious discussions and analyses of X emerged during the 1970s with …
Over the past two decades, major advances in molecular biology have allowed …
Historically, research investigating the factors associated with X has focused on …
It is only since the work of Smith (2001) that the study of X has gained momentum.
The construct of X was first articulated by Smith (1977) and popularised in his book: …
Around the early 1960s, small-scale research and case studies began to emerge linking …
It was not until the late 1960s that historians considered X worthy of scholarly attention.
Awareness of X is not recent, having possibly first been described in the 5th century BCE by …
Most research on X has been carried out in …
Most researchers investigating X have utilised …
Using this approach, researchers have been able to …
Several systematic reviews of X have been undertaken.
The vast majority of studies on X have been quantitative.
What we know about X is largely based on observational studies.
There are a number of large cross-sectional studies which suggest …
Much of the previous research on X has been exploratory in nature.
Much of the X research has focused on identifying and evaluating the …
What we know about X is largely based upon empirical studies that investigate …
Publications that concentrate on X more frequently adopt a historical or chronological approach …
| What we know about X is largely based upon | case clinical empirical qualitative simulation laboratory longitudinal comparative experimental observational epidemiological | studies that investigate … |
To date, several studies have investigated …
A number of studies have begun to examine …
Various studies have assessed the efficacy of …
Researchers attempted to evaluate the impact of …
A great deal of previous research into X has focused on …
Several studies have used longitudinal data to examine …
Previous studies have explored the relationships between X and Y.
Twenty cohort study analyses have examined the relationship between …
A number of authors have considered the effects of … (Smith, 2003; Jones, 2004).
At least 120 case-control studies worldwide have examined the relationship between …
Numerous studies have attempted to explain … (for example, Smith, 1996; Jones, 1998; …).
Several lines of evidence suggest that …
Previous research has established that …
Data from several studies suggest that …
Recent evidence suggests that … (Smith, 2020; …).
It is now well established from a variety of studies that …
New findings amongst X provides further evidence that …
A number of studies have postulated a convergence between …
Recently, considerable evidence has accumulated to show that …
Surveys such as that conducted by Smith (2015) have shown that …
Many recent studies (e.g. Smith, 2019; Jones, 2020) have shown that …
Traditionally, it has been argued that … (e.g. Smith, 1960; Jones, 1972).
Several biographies of Brown have been published. Smith (2016) presents …
In previous studies on X, different variables have been found to be related to …
Many historians have argued that … (e.g. Jones, 1997; Brown, 1999; Smith, 2019).
There is a consensus among social scientists that … (e.g. Smith, 2019; Jones, 2020; …
Data from several sources have identified the increased X and Y associated with obesity.
Recently, in vitro studies have shown that X can … (Smith et al., 2018; Jones et al., 2021).
It has been demonstrated that a high intake of X results in damage to … (Smith, 2015; …).
| To date, Thus far, Up to now, | several studies previous studies a number of studies | have | used … found … reported … shown that… indicated that … linked X with Y. suggested that … demonstrated that … begun to examine the use of … confirmed the effectiveness of … revealed a correlation between X and Y. highlighted factors that are associated with … |
X increases when … (Smith, 2015)
X is able to affect Y (Smith, 2015; Jones, 2020).
X is positively related to Y (Smith, 2015; Jones, 2020).
X is proportional to Y as expressed by the… (Smith, 2015).
X is one of the most important … (Smith, 2015; Jones, 2020).
X is one of the most intense reactions following Y (Jones, 2020).
A relationship exists between X and Y (Smith, 2015; Jones, 2020).
X is a principal determining factor of Y (Smith, 2015; Jones, 2020).
There is an unambiguous relationship between X and Y (Smith, 2015).
X is significantly reduced during the first months of … (Smith, 2015; Jones, 2020).
X has been found to oppose the anti-inflammatory actions of Y on Z (Smith, 2020).
Smith’s comparative study (2017) found that …
Jones’s comprehensive review concluded that …
Brown’s (1998) model of X assumes three main …
Smith’s cross-country analysis (2017) showed that …
Jones’s (2010) review of the literature concluded that …
Brown’s (2022) recent analysis of X provides a strong critique of …
| Smith (2015) | reported … identified … showed that … demonstrated that … found that as levels X rise … |
| Jones (2015) | compared the rate of … labelled these subsets as … measured both components of the … used a survey to assess the various … investigated the differential impact of … identified parents of disabled children as … set up a series of virtual experiments using … examined the flow of international students … carried out a number of investigations into the … studied the effects of X on unprotected nerve cells. conducted a series of trials in which she mixed X with … analysed the data from 72 countries and concluded that … interviewed 250 undergraduate students using semi-structured … performed a similar series of experiments in the 1960s to show that … reviewed the literature from the period and found little evidence for this … |
In 1959, a seminal article was published entitled …
Following this period, Smith actively searched for X.
In the 1950s, Smith pointed to some of the ways in which …
Thirty years later, Smith (1974) reported three cases of X which …
Almost 20 years ago, Jones (1995) formulated his X theory, centred around …
| In 1990, | Smith et al. | found that … performed the first … published a paper in which they described introduced a system of classification based on … demonstrated that X induced in vitro resistance to reported a new and convenient synthetic procedure to … |
One longitudinal study found that …
A seminal study in this area is the work of …
One study by Smith (2014) examined the trend in …
A recent study by Smith and Jones (2012) involved …
A qualitative study by Smith (2003) described how …
A recent systematic literature review concluded that …
Preliminary work on X was undertaken by Jones (1992).
A longitudinal study of X by Smith (2012) reports that …
A key study comparing X and Y is that of Smith (2010), in which …
The first systematic study of X was reported by Smith et al. in 1986.
Detailed examination of X by Smith and Jones (1961) showed that …
Analysis of the genes involved in X was first carried out by Smith et al. (1983).
A significant analysis and discussion on the subject was presented by Smith (1988).
The study of the structural behaviour of X was first carried out by Jones et al. (1986).
A small scale study by Smith (2015) reached different conclusions, finding no increase in …
The study by Jones (1990) offers probably the most comprehensive empirical analysis of …
| In a(n) | follow-up study, major study of X, investigation into X, study investigating X, comprehensive study of X, recent cross-sectional study, large-scale longitudinal study, randomised controlled study of X, study which set out to determine X randomised controlled study of X, | Smith et al. (2015) | found … reported … |
To determine the effects of X, Jones et al. (2005) compared …
X was originally isolated from Y in a soil sample from … (Jones et al., 1952).
The electronic spectroscopy of X was first studied by Smith and Jones in 1970.
X formed the central focus of a study by Smith (2002) in which the author found …
To better understand the mechanisms of X and its effects, Jones (2013) analysed the …
X was first demonstrated experimentally by Pavlov (Smith, 2002). In his seminal study …
The acid-catalyzed condensation reaction between X and Y was first reported by Smith in 1872.
The way in which X is regulated was studied extensively by Smith and colleagues (Smith et al. 1995 and 1998).
In Chapter 2, Smith provides us with a number of important …
In the subsequent chapter, Smith examines the extent to which …
By drawing on the concept of X, Smith has been able to show that …
Some analysts (e.g. Smith, 2015) have attempted to draw fine distinctions between …
Drawing on an extensive range of sources, the authors set out the different ways in which …
Other authors (see Smith, 2010; Jones, 2014) question the usefulness of such an approach.
| Smith (2000) | defines X as … questions whether … lists three reasons why … identifies X, Y, and Z as the major causes of … draws on an extensive range of sources to assess … traces the development of X during the 19th century. highlights the need to break the link between X and Y. mentions the special situation of X as an example of … uses examples of these various techniques as evidence that … draws our attention to distinctive categories of X often observed in … discusses the challenges and strategies for facilitating and promoting … considers whether countries work well on cross-border issues such as … provides in-depth analysis of the work of Aristotle showing its relevance to … |
| In her review of …, In her major study, In her analysis of …, In her seminal article, In her case study of …, In her introduction to …, In her classic critique of …, In her interesting analysis of …, | Smith (2012) identifies five characteristics of … |
As noted by Smith (2003) X is far more cost effective, and therefore …
According to Smith (2003), preventative medicine is far more cost effective, and therefore …
| Smith (2013) | argues claims suggests maintains concludes points out | that | preventative medicine is far more cost effective, and therefore better adapted to the developing world. |
| Smith (2013) | offers proposes suggests argues for | an explanatory theory for each type of irrational belief. |
Similarly, Jones (2015) found that X …
This is consistent with the data obtained by …
Smith (1995) makes a similar point in his study of X …
In the same vein, Smith (1995) in his book XYZ notes
This view is supported by Jones (2015) who writes that
Along the same lines, Smith (1995) subsequently argued that …
Smith argues that her data support Jones’s (1995) view that
Jones’s (1986) work on X is complemented by Smith’s (2009) study of
Almost every paper that has been written on X includes a section relating to
A broadly similar point has also recently been made by Johnson (2019), who …
| Smith (2015) | sees X as … argues that … | Like Smith, Jones (2016) maintains that … Similarly, Jones (2016) makes the case for … Likewise, Jones (2016) holds the view that … Supporting this view, Jones (2016) writes that … Adopting a similar position, Jones (2016) argues that … In the same vein, Jones (2016), in his book XXXXX, notes … |
Other writers have argued that …
Other studies have concluded that …
Unlike Smith, Jones (2013) argues that
In contrast to Smith, Jones (2013) argues that
Smith (2010) presents an X account, whilst Jones (2011)
While Smith (2008) focuses on X, Jones (2009) is more concerned with
A broader perspective has been adopted by Smith (213) who argues that
Contrary to previously published studies, Jones et al. demonstrated the efficacy of…
This result conflicts with Smith’s (1965) previously mentioned study which found that …
Conversely, Smith (2010) reported no significant difference in mortality between X and Y.
| Some writers (e.g. Smith, 2002) have attempted to draw fine distinctions between … break Some authors have mainly been interested in questions concerning X and Y (Smith, 2001; Jones … break Much of the available literature on X deals with the question of … | Others (see Jones, 2003; Brown, 2004) question the usefulness of … break Others have highlighted the relevance of … break But Smith (2015) is much more concerned with … |
| Smith (2015) notes that … break Smith (2013) found that X accounted for 30% of Y. | However, Jones’s (2018) study of Y found no link between … break Other researchers, however, who have looked at X, have found … Jones (2010), for example, … |
| Smith (2010) presents an X account, break While Smith (2008) focusses on X, | whilst Jones (2011) … break Jones (2009) is more concerned with … |
Commenting on X, Smith (2003) argues: ‘… …’
As Smith (2004: 215) states: ‘there are many good reasons to be sceptical’.
As Smith argues: ‘In the past, the purpose of education was to …’ (Smith, 2000:150).
In the final part of the Theses on Feuerbach, Marx writes: ‘Philosophers have hitherto only …’
Smith concludes: ‘The idea of development stands today like a ruin in …’ (Smith, 1992: 156).
| As Smith (2015: 320) | notes: ‘… … … … … ‘ argues ‘ … … … … … ‘ writes: ‘ … … … … … ‘ observes: ‘ … … … … … ‘ points out: ‘ … … … … … ‘ reminds us: ‘ … … … … … ‘ |
Together, these studies indicate that …
Overall, these studies highlight the need for …
Considering all of this evidence, it seems that …
Collectively, these studies outline a critical role for…
In all the studies reviewed here, X is recognised as …
The evidence presented in this section suggests that …
The studies presented thus far provide evidence that …
Taken together, these studies support the notion that …
Overall, there seems to be some evidence to indicate that …
Together these studies provide important insights into the …
All of the studies reviewed here support the hypothesis that …
Two important themes emerge from the studies discussed so far:
However, such studies remain narrow in focus dealing only with …
The evidence reviewed here seems to suggest a pertinent role for …
These studies clearly indicate that there is a relationship between …
In view of all that has been mentioned so far, one may suppose that …
There remain several aspects of X about which relatively little is known.
| Overall, these studies | show … suggest … provide … indicate … highlight … |
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