Extracts, &c. calculated to assist inquiry as to the probable or actual existence of coal in any given district. South African Quarterly Journal, Cape Colony, v. 1, n. 1, p. 71–79, 1830. DOI: 10.21504/saqj.11.2619. Disponível em: https://journal.ru.ac.za/index.php/saqj/article/view/2619. Acesso em: 20 nov. 2025.