Gaya APA

Verstappen, H, T. (1973). A Geomorphological Reconnaissance of Sumatera & Adjacent Islands (Indonesia) . : Groningen, Wolters Noordloff..

Gaya MLA

Verstappen, H., Th.. "A Geomorphological Reconnaissance of Sumatera & Adjacent Islands (Indonesia)". : Groningen, Wolters Noordloff., 1973. Text.