Childe, V. G., & Clark, G. (1942). What happened in history. Penguin books.
Citazione stile Chigago Style (17a edizione)Childe, V. Gordon, e Grahame Clark. What Happened in History. Baltimore: Penguin books, 1942.
Citatione MLA (8a ed.)Childe, V. Gordon, e Grahame Clark. What Happened in History. Penguin books, 1942.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.