Compare:Walker, Eric Anderson (1936). “14: The Formation of new states, 1835-1854”. In Walker, Eric Anderson. The Cambridge History of the British Empire. 8: South Africa, Rhodesia and the protectorates. Cambridge: Cambridge University Press. pp. 320?321. https://books.google.com/books?id=ISg9AAAAIAAJ2018年9月15日閲覧. "In the latter part of 1834, the frontier districts were full of talk of a mass trek. Exploring parties rode out to South-West Africa, to the north-eastern Transvaal, and along the coast belt to Natal. [...] These preparations are conclusive evidence against the traditional idea that the two primary causes of the Great Trek were the inadequate compensation paid for emancipated slaves and the upsetting of D'Urban's settlement of the eastern frontier after the Kaffir War of 1834?5 by the combined forces of Downing Street and Exeter Hall. It is true that many Trekkers, and those the most vocal, came from the eastern frontier lands, but others came from the northern districts where there was no Kaffir menace. The overthrow of the settlement was only a subsidiary cause though a powerful one."
J. A. Heese (1971) (アフリカーンス語). Die herkoms van die Afrikaner, 1657?1867 [The origin of the Afrikaner]. Cape Town: A. A. Balkema. OCLC1821706. OL5361614M
J. A. Heese (1971) (アフリカーンス語). Die herkoms van die Afrikaner, 1657?1867 [The origin of the Afrikaner]. Cape Town: A. A. Balkema. OCLC1821706. OL5361614M
Christopher, Riches; Palmowski, Jan (1965). A dictionary of contemporary world history : over 2800 entries. ISBN9780191802997. OCLC965506087
