Gaya APA

Aspden, J. (1982). Geologi lembar Padangsidempuan dan Sibolga, Sumatra = The geology of the Padangsidempuan dan Sibolga Quadrangle, Sumatra . Bandung: Geological Research and Development Center.

Gaya MLA

Aspden, J.A.. "Geologi lembar Padangsidempuan dan Sibolga, Sumatra = The geology of the Padangsidempuan dan Sibolga Quadrangle, Sumatra". Bandung: Geological Research and Development Center, 1982. Text.