Kassil, L. (1964). Was ist Glück? Kinderbuchverlag.
Citazione stile Chigago Style (17a edizione)Kassil, Lew. Was Ist Glück? Berlin: Kinderbuchverlag, 1964.
Citatione MLA (8a ed.)Kassil, Lew. Was Ist Glück? Kinderbuchverlag, 1964.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.