D. Walsh, P., J. Michael Fay, S. Gulick, and G. . Phillipe Sounguet. “Humpback Whale Activity Near Cap Lopez, Gabon”. J. Cetacean Res. Manage., vol. 2, no. 1, Apr. 2000, pp. 63-67, https://journal-iwc-live.netxtra.dev/index.php/jcrm/article/view/489.