De Haan embarked on her literary career by writing articles and stories for Dutch magazines, using the pseudonyms "Cissy van Marxveldt", "Betty Bierema" en "Ans Woud". In the year she married (1916), she published the first book in what was to become a series of novels about a headstrong girl, Joop ter Heul. The books, similar in theme to Louisa May Alcott's Little Women, contain many diary entries and letters. They chart the fortunes of Joop, her sister and her school friends, from girlhood through marriage. The series consists of five volumes: