Select the most important 2-3 ideas related to your topic. Put the word AND between each new term; this tells the database to look for resources with ALL your terms.
jet design AND physics
Use quotation marks ( " " ) around phrases (two or more words); this tells the database to look for the words in a specific order.
"jet design" AND physics
Use an asterisk ( * ) to find multiple versions of one word. Using atom* as a search term will include results that refer to atom, atoms or atomic.