Roth, B. and Tupen, J. 2004. Revision of the systematic status of Helminthoglypta walkeriana morroensis (Hemphill, 1911) (Gastropoda: Pulmonata). Zootaxa. 616, 1 (Aug. 2004), 1–23. DOI:https://doi.org/10.11646/zootaxa.616.1.1.