A common search technique is to use a connector such as AND, OR, or NOT. These operators tell the search engine to include (or exclude) certain words. For instance, a search for bees and disease returns 58 million results in Google, but bees and parasite and afb will return about 170,000 results because you are asking for all those terms to show up in the results. Searching bees and parasite or afb will expand your search results to 275,000 because you are searching for pages that include the word bees and the word parasite or the word afb.
Searching bees and "american foulbrood" tells Google you want to search both the word bees and the phrase "american foulbrood" . This returns about 108,000 results, many of which are from .org and .edu sources which means the sources are organizations or educational institutions.
You can search a specific website by typing in the name of the site followed by a colon eg: nytimes.com: bees . This is a quick way to get a list of results from a specific site and it works in most web search environments such as Google, Bing, and DuckDuckGo.
Both the phrase search and site: operator are mentioned in a very good article in the NY Times titled
6 Google Tricks That Will Turn You Into an Internet Detective.
Most databases offer an Advanced Search option with search fields you can link using built-in connectors.
CUNY OneSearch has an advanced Search option that looks like many of the subscription databases.
EBSCO offers a consistent look and feel across its many databases. You can stack terms or enter search criteria in a single field.
Operators may vary depending on the database vendor or publisher. Look for the search rules that apply to what you are searching.