I was trying to help someone to formulate a search strategy for the topic of "nutrition programs." She wanted to know if she should search using the spelling -program- or -programme-
The answer is that you should search for both. You don't want to eliminate records from your search results just because the author spells differently from you.
The easiest way to accomodate for variant spellings is to incorporate wildcard characters into your search. In most databases, you can retrieve all variations of a word by adding an asterisk at the end of it (as in: program*) Wildcards vary from database to database, (you might find yourself using program! or program$ or program%) so you should consult the help pages of the database you're using if you don't get the results you wanted.
(NB: The Google search interface doesn't support wildcard characters)