Original: Characters and behaviors in the movie are based on Fey's high school life at Upper Darby High School and on the non-fiction book Queen Bees and Wannabes by Rosalind Wiseman.
Simplified: Characters and behaviors in the movie are based on Fey's high school life at Upper Darby High School. It is also based on the non-fiction book Queen Bees and Wannabes by Rosalind Wiseman.