General remark: AllThatStats’ algorithms try to do the work for you. E.g., they automatically interpret “GDP” as “Gross Domestic Product”. But sometimes manual interaction might be requested. In this case, AllThatStats provides a number of advanced search commands that will help you quickly find what you are looking for.
“AND” is the standard operator, search terms without specifying an operator are interpreted as “AND” search: find sources that have all the words shown in your search term
“OR” search for one term or the other
“-” a hyphen/minus stands for “NOT”: search not for terms with a leading not-operator