H. F.  Howden and Peck, S. B., ?Collecting in El Salvador, with particular reference to Scarabaeoidea and Silphoidea (Coleoptera)?, The Coleopterists Bulletin, vol. 26, pp. 63-72, 1972.

S. B.  Peck and Howden, H. F., ?Response of a Dung Beetles Guild to Different Sizes of Dung Bait in a Panamanian Rainforest?, Biotropica, vol. 16, pp. 235-238, 1984.

S. B.  Peck and Howden, H. F., ?Response of a dung beetle guild to different sizes of dung bait in a Panamanian Rainforest?, Biotropica, vol. 16, pp. 235-238, 1984.