Hoffman, Richard L. 2011. “A Review of the Milliped Genus Haplogonopus With Commentary on the so-Called ‘Charactopygus-Bildung’ Modification of Spirostreptid Paraprocts (Diplopoda: Spirostreptidae)”. Zootaxa 2734 (1). Auckland, New Zealand:53–62. https://doi.org/10.11646/zootaxa.2734.1.4.