Aalbu, R.L., Spilman, T.J. & Brown, K.W. (1995). The systematic status of Amblycyphrus asperatus, Threnus niger, Pycnomorpha californica, Emmenastus rugosus, and Biomorphus tuberculatus Motschulsky (Coleoptera: Tenebrionidae). Proceedings of the Entomological Society of Washington. 97: 481-488.
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Aalbu, R.L., Spilman, T.J. & Brown, K.W.
1995
The systematic status of Amblycyphrus asperatus, Threnus niger, Pycnomorpha californica, Emmenastus rugosus, and Biomorphus tuberculatus Motschulsky (Coleoptera: Tenebrionidae).
Proceedings of the Entomological Society of Washington