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Biology: BIO 305

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Best Bets for Literature Review

The databases listed below are some recommended options for tracking down resources to use in your literature review. If you need a refresher on how to best use them, contact me!

Boolean and other operators

Operators are symbols or words that, when combined with search terms, help to either limit or expand your searches. They are important tools for streamlining the search process, but they can be tricky to use correctly and effectively. Here are some common operators and general rules for using them.


Boolean operators

Boolean operators are used to define the relationship between search terms. They can be used to broaden or narrow a set of search results. There are three common Boolean operators: AND, OR, and NOT. It's good practice to capitalize Boolean operators because some databases require it.

AND is used to join words or phrases when both (or all) the terms must appear in the items you retrieve.

This search query would return a much smaller set of records, and the items found would be more specific to your research question. If you are retrieving too many records, try adding another search term with the Boolean Operator AND.

animated Venn Diagram of AND boolean search

OR is used to join synonymous or related terms, and instructs the search tool to retrieve any record that contains either (or both) of the terms, thus broadening your search results.

The OR operator is particularly useful when you are unsure of the words used to categorize your topic or if information on your topic is even available. If you are retrieving too few records, broaden your search by adding a synonym with the Boolean Operator OR.

animated Venn diagram of OR boolean search

NOT is used to exclude a particular word or combination of words from your search results.

If you are retrieving many records that are unrelated to your topic, try using the NOT operator to eliminate a word. This should be done cautiously, because as well as deleting the unwanted items, such a search will also eliminate records that discuss both the relevant topic as well as the unrelated topic.

animated Venn diagram of NOT boolean search




Truncation is used to search all terms that begin with a common stem. Databases tend to be very literal in interpreting your queries, and, for example, won’t return plurals of words if you just type in the singular form (some search systems are capable of doing this automatically, but you can’t assume). If a term you are searching has variants with the same beginning but various suffixes or endings, use truncation to capture all these. The symbol most commonly used for this is an asterisk. For example:

comput* = computer, computing, computation…

Use the asterisk to replace the last few letters of the word. The asterisk means “any character(s) (or none) can be here.” Be careful where you truncate – in the above example, truncating back to comp* would give back a mess of different things (e.g., competition), while compute* would eliminate some of the relevant variants.

Be careful with this technique! It can backfire pretty easily. Do not try to truncate short words like cat or rat, as you’ll bring back too much irrelevant stuff, like catastrophe. Instead search on the particular variants you need, e.g. cat OR cats. Also note that you cannot truncate “backwards” – computers* isn’t a very useful construct, as no other words begin with “computers”.


Phrase Searching

In many databases it is possible to search for sets of words immediately adjacent to each other, i.e. phrase searching. How this works depends on the database. In some, typing two or more words together, e.g. house cat, implies searching for the words together. In other search tools (including Web of Science, and Google), searching on the two words means the same as a Boolean AND search, e.g. house cat is the same as house AND cat; while putting the phrase in quotation marks demands the terms be searched as a phrase, e.g. “house cat”. Consult the database help, or try these possibilities and see what you get.

Best practice is to use quotations around the phrase you want to search. Most databases will recognize this as a phrase search, even if it doesn't require it, and you'll develop a good habit for the databases that do require it.

Searching the Literature

Searching the literature for articles and information related to your topic can be very time-consuming, but it's an important step in the research process. A good literature search will give you the background information you need to understand and interpret the data you were given for your assignment.

Use the steps below to help you brainstorm your search terms and combine them in meaningful and helpful ways.

Step 1: Identify major concepts

Take a look at the purpose and procedures for the topic you were given, and break it down into large concepts or ideas. For example, let's say I'm looking into ion transport in frogs infected by chytrid. I've broken it out into three concepts to illustrate the process, but you shouldn't feel limited to having just three main ideas. 

Concept 1 Concept 2 Concept 3


chytrid ion transport

Step 2: Identify related terms

For each concept or idea, identify any synonyms or related terms. This is what you'll use as your keywords (combined with Boolean operators) when searching our databases.

Concept 1 Concept 2 Concept 3







ion transport

electrolyte transport

drink patch

pelvic patch

You'll notice in the terms I've listed for Concept 3, they're not all synonyms for each other, but they are related. To best combine these terms, you may need to get a little creative with your operators. You can use parentheses in conjunction with Boolean operators to better limit your search. For example:

((ion OR electrolyte) AND transport) OR (drink OR pelvic) AND patch)

Remember the order of operation from algebra? The parentheticals here function the same basic way. This will search for all papers that mention ion AND transport, electrolyte AND transport, drink AND patch, or pelvic AND patch.

Using parentheticals properly with Boolean operators will save you a lot of time and frustration, but it can be a little strange to wrap your head around. Don't hesitate to reach out if you run into any trouble, or aren't sure if what you're doing is correct.

Step 3: Combine

Once you've got your concepts and terms laid out, it's time to start searching. Pick your database (Web of Science is highly recommended) and go! The related terms for each concept should go in one field, combined by OR, and your fields containing your concept terms should be combined by AND. Also keep in mind that you can use truncation to find all words with the same prefix, to save yourself some headaches. For example:

frog OR anura*


chytrid* OR Batrochochytrium OR Bd


((ion OR electrolyte) AND transport*) OR (drink OR pelvic) AND patch)

Keep in mind that the first list of keywords you create may not get you enough relevant material to be 100% useful to you. Literature searching has no one right answer; it make take you a several passes using different keywords in different combinations to find all the information you need. Don't give up! And don't hesitate to reach out to me if you need some guidance at any point in this process.

Get to Full Text with Find It!

Most literature indexes do not have the actual journal articles included within them.  Instead, these indexes just contain information about the article, e.g. titles, authors, abstract.

When you find an article of interest in an index, click the "Find It" button by that entry to get to the full text.  If we have a subscription, "Find It" will provide a link to the journal article. (Or if we have the print, it will provide a link to the catalog with the location and call number.)

Find It button

(A few databases, like Academic Search Complete, include full text for some articles. These databases may allow you to search only for articles available in full text, but be aware that you are only searching a small portion of the articles we actually subscribe to.)

New to searching for literature?

This series of short videos will show you a few useful techniques you can use to improve your literature searches.


Your Librarian

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Ginny Boehme

My appointment scheduler is open for you to meet with me virtually. The default platform I use is Zoom, but if you prefer Google Meet or WebEx, that's not a problem at all.

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Citation Managers

The links below will give you more information about a few free citation managers. They've got a bit of a learning curve, but pretty much everyone who uses one considers it a game-changer. Please let me know if you want to learn more about any of them!