[Pro Tip – Don’t actually use Bing for literature searches…. it’s remarkably bad]
Starting a new project the first time, whether it be starting graduate research in a new lab, starting a new postdoc, or as a PI with a new collaboration, means that you are going to need to get an idea of what has been done. But with hundreds of thousands of peer reviewed articles published yearly over the past several decades, the idea of diving in can be a bit daunting. Maybe you have no idea where to start. But you need to get an idea of what’s been done and what hasn’t; the sooner you can search the literature, the better.
My hope is that this will give you a framework to start sifting through the mountains of literature on a new topic, as well as an idea of the tools and methods that I use when I search the literature for a new topic.
Disclaimer: the tools that I use are more specific to engineering and biomedical research disciplines. While they may be applied to social science and liberal arts research disciplines, there may be better tools for those research disciplines.
Outline Your Goals
Before you start searching, there some guiding questions you should ask yourself about what you are looking for:
[I discuss these sorts of questions further in this post on understanding your new field of research]
What is the goal of this search?
To get an idea of what you need to start searching, it’s good to have a goal in mind. Are you trying to see where the community stands on the molecular mechanisms of addiction? Maybe you want to see how Raman spectroscopy is used for surgical guidance? It’s good to have a general overarching idea to help guide your search. From this, you can begin to identify subsection or subfields within your overarching idea. For addiction mechanisms, you may be interested in identifying pre- and post-synaptic pathways, the role of reward circuits in the behavioral manifestations of addiction. For intraoperative Raman spectroscopy, you may separate your search into cancer-detection vs. non-cancer applications vs. infectious disease applications. You might even separate work by medical field like endocrine, neurosurgical, gastrointestinal, otolaryngologic, etc. Continuing to break these ideas down as you search will help organize your thoughts quite a bit. And building a web or a detailed outline might be even more helpful.
What are some keywords you can look into?
It’s good to have some more directed guiding keywords. For example, typing ‘Raman Spectroscopy’ is going to lead you down an aimless rabbit-hole spanning archeology, art history, chemistry, nanoscience, diagnostic medicine, and so much more. Since Raman is typically used as a research tool, its important to tailor searches to be more specific with keywords. Some examples might be ‘Clinical Applications of Raman Spectroscopy’ or ‘Raman Spectroscopy for Nanomaterials Characterization,’ ‘Resonance Raman in Ophthalmology,’ etc. Realistically, the more narrowly defined the questions, the better off you will be to begin searching through the literature. Keep a running list of key words as you search to continue refining your searches.
Once you have an idea of where to start, you can begin moving on to searching databases.
Talk to Others
If you are joining a new lab, it would not be a bad idea to ask around the lab if anybody has a good review article they can point you to. Maybe ask your PI or a collaborator if they can direct you to any particularly notable works that will give you a point to jump off from. Use these suggestions to start building up your body of work, by browsing who has cited those papers and what papers are cited within those papers. Review papers can be an awesome jumping-off point.
Every literature search normally begins with a keyword search in a database. Not all databases are created equally. Some are good for some things more than others. To be as comprehensive as possible, it’s wise to use more than one database for your searches.
Google has built a massive enterprise off of its search engine. And it does a decent job with searching the literature. It indexes the most popular literature repositories like Elsevier, ScienceDirect, etc. One of the strongest points of Google Scholar is that it indexes literature very quickly, as soon as a couple days following publications. But that says, it has its drawbacks.
One of the downfalls of Google that I have noticed is that it gives preferential indexing to newer publications. Anything before the year 2000 can be found, but they may not always show up towards the top of searches, which can be problematic in many fields of research. [Side-note: DO NOT SKIP OVER OLD LITERATURE. There are many valuable lessons, conclusions, and lines of thinking presented in older literature)Additionally, they index works that are subject to less rigorous (and potentially predatory) peer-review channels, which can be misleading if not read and reasoned carefully. Google has a tendency to generate multiple items for a single article, which can skew its citation and misrepresent impact. This varies from field to field, and Google is actively working to improve its indexing. If you are using Google Scholar, the best way to ensure you are getting the best access to the available literature is to use it through a your institutional or public library, which gives you access to a more robust collection of work. By no means should Google Scholar be the only database you end up searching.
Web of Science
Clarivate Analytics, formerly Thompson-Reuters, run the Web of Science (WoS) database. This is my go-to database for literature searches. Compared to Google, WoS is much more picky about it’s indexing sources. Anything indexed on WoS has been through rigorous peer review, which helps you sleep better knowing that you are not condoning shoddy work or predatory publishing. It allows you to sort search results based on date of publications and number of citations, which is useful for finding key pieces of literature. That said, it comes with its drawbacks.
Accessing WoS requires to go through a library or academic institution. Additionally, WoS is terribly slow at indexing new publications, between 2 and 6 months post publication. The time to indexing the biggest reason that I do not rely solely on WoS for literature searches. It’s okay to rely on WoS for publication quality and depth of indexing.
Like Google Scholar, it’s important to use WoS through your institutions or local library’s proxy system to ensure you are getting access to the most work available.
PubMed is kept and maintained by the NIH (NCBI, more specifically). As such, you are able to access any NIH-sponsored research through it relatively easily. The drawback to this is that you likely less successful in locking down full text from any non-NIH-funded papers. A lot of times PubMed will still index the work, but not have access to the full text. Other times the work will not be indexed at all. This may be more or less important to you depending on what type of research you do.
One really nice thing about PubMed is that it suggests papers to you based off of your searches. This often can lead to you big name works that you might have missed, other tangentially related but highly cited works, or some lesser known but relevant studies that can be easily overlooked. This feature has gotten me a number of extra papers that I had initially missed. I always browse the suggestions when I’m looking for papers now. Elsevier and ScienceDirect have this feature with papers that they index and host, and I like to use those suggestions as well. But the three aforementioned databases often link out to these pages, so you will likely stumble across them in some form as you continue to search.
You cannot conduct a literature search just from the database. There are too many results to sift through, you are inevitably going to miss something. And that’s okay. The search you perform in the database ultimately lays the groundwork to finding a lot of the relevant work to your field. The next step comes from searching the works cited lists from each paper. Especially review papers and highly-cited works, WoS indexes paper’s citations and well as the papers that cite a particular paper. It’s critical to dive into these lists of work, which will give you a very robust survey of the literature in a particular field.
You cannot solely rely on the highly cited works to give you a view of the literature. It’s important to dive into the work that each paper cites. The story is often elucidated in a piecewise manner by many people across the globe. It’s important to understand the questions, answers and justification that each work addresses to get a true survey of the field.
If you really want to stay current on a particular field, I posted about how to set up and use an RSS feed to stay caught up with what’s being published. RSS feeds are a great way to streamline your acquisition of new information across a number of sites and platforms. Additionally, if you are in the market for a citation manager, I have a post on that as well.
The next best way to stay up to date is to browse and attend conferences in your field. For me, SPIE Photonics West BIOS and OSA Biophotonics Congress are two major conferences that I try to keep up-to-speed with in my field. There are a LOT of talks to sift through, but it’s a great way to get an idea of what research is actively happening, often months before you see a print publication. Oftentimes, if you cannot attend, I know SPIE will actually post videos of many talks on their proceedings platform, SPIE Digital Library [you can see my first talk on SPIE Digital Library here]. But if you can, attending these conferences gives you a great networking opportunity with the students and researchers conducting the research, as well as get multiple perspectives the current state of research. Try to convince your advisor to get you at least one, hopefully two conferences a year.
These are some of the tips that I use when I start to pursue a new avenue of research. Brainstorming topics and keywords ahead of time, talking to colleagues, using multiple databases, digging through key paper citation lists (both works cited, and cited by), and staying current with works are the main methods I use to compile literature. There are plenty of other strategies out there, and I encourage you to discuss with your peers and colleagues. The more methods you have, the better.
Do you have any literature search tips that I did not mention? Leave a comment or shoot me a tweet!