You may combine previous searches by clicking on the “Search History.” (See screen shot below.)
Check the searches you wish to combine and check the Boolean (logical) operator you wish to use to combine them (“and,” “or"). Click on “Add.”
Or type “s” (without the quotation marks) and the search number in the search box.
You can use Boolean operators to combine previous searches or use previous searches with new terms. Examples: s1 and s2 s2 and phobias (s1 or phobias) and anxiety