Clarke, E. (1974). Objective tests in O Level history: Europe and the Modern World 1870 - 1970. Murray.
Citazione stile Chigago Style (17a edizione)Clarke, Ernest. Objective Tests in O Level History: Europe and the Modern World 1870 - 1970. London: Murray, 1974.
Citatione MLA (9a ed.)Clarke, Ernest. Objective Tests in O Level History: Europe and the Modern World 1870 - 1970. Murray, 1974.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.