Lisa Birnbach 's tongue-in-cheek guides , `` The Official Preppy Handbook '' and its sequel `` True Prep : It 's a Whole New Old World '' , feature Lilly Pulitzer clothing as must-have items for `` preppy '' women .
Lisa Birnbach 's humorous `` guides '' , `` The Official Preppy Handbook '' and its sequel `` True Prep : It 's a Whole New Old World '' , say Lilly Pulitzer clothing is a must-have item for `` preppy '' women .