Não informado. (1974). History and social science teacher. Ontario History and Social Science Teachers Association.
Citação do estilo Chicago (17ª ed.)Não informado. History and Social Science Teacher. Toronto, Canada: Ontario History and Social Science Teachers Association, 1974.
Citação MLA (8ª ed.)Não informado. History and Social Science Teacher. Ontario History and Social Science Teachers Association, 1974.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.