What Is a Resumé Hole and How Do I Fill It?
http://sciencecareers.sciencemag.org/career_development/previous_issues/articles/0770/what_is_a_resume_hole_and_how_do_i_fill_it

Kitts, Adrienne
Science
2001

Abstract:

Usually, a resumé will show a chronology of a professional career that is almost continuous. But what if the unexpected happens, and you are left with a "resumé hole"? A resumé hole is a large period of unaccounted time in your resumé.