Published in Transactions of the South African Philosophical Society, in 1889, in volume 6, issue 1, pages 1-16

Published in Transactions of the South African Philosophical Society, in 1889, in volume 6, issue 1, pages 17-30

Published in Transactions of the South African Philosophical Society, in 1889, in volume 6, issue 1, pages 31-38

Published in Transactions of the South African Philosophical Society, in 1889, in volume 6, issue 1, pages 39-43

Published in Transactions of the South African Philosophical Society, in 1889, in volume 6, issue 1, pages 44-51

Published in Transactions of the South African Philosophical Society, in 1889, in volume 6, issue 2, pages 95-135