Look for options to refine your search by type of source, full text, date, etc.
Use wildcard characters. If searching for economic conditions, type the word econ* with an asterisk. That will return economies, economic, economist and any word that starts with econ.
Try using Boolean operators: AND, OR, NOT. For example: "World’s Fair New York 1939" AND "youth"
Use quotation marks to search for the words that are next to each other. For example, New York World's Fair looks for any search results that contain those four words, while "New York World's Fair" looks for those words next to each other in the search results.