Select the most important 2-3 ideas related to your topic. Put the word AND between each new word or idea; this tells the database to look for resources with ALL your terms.
hepatitis AND vaccine
Use quotation marks ( " " ) around phrases:
"hepatitis A" AND vaccine
Use the asterisk (*) to truncate a word; this tells the database to look for all words that have the same base. In the example below, search results would include vaccine, vaccinate, vaccinates, vaccination, vaccinations, etc.
"hepatitis A" AND vaccin*