VILLWOCK, Gerd. Small-scale geomorphological mapping of P.D.R. of Yemen: an approach to landscape evaluation. Geografia Fisica e Dinamica Quaternaria, [S. l.], v. 2, p. 93–96, 1989. Disponível em: https://www.gfdq.glaciologia.it/index.php/GFDQ/article/view/1141.. Acesso em: 30 may. 2026.