In addition to Dobrin's original field recordings of Cemaun and closely related dialects of Mountain Arapesh, several other resources on Arapesh languages are collected in the AGDLA archive:
Reo Fortune's 1942 grammar of Mountain Arapesh (Rohwim dialect) is available here in digital form.
A collection of line-glossed Bukiyip texts.
These were produced by linguist Robert J. Conrad over his two-decade-long station in the Arapesh region. Conrad worked in New Guinea as a mission linguist with the Bible translation organization SIL International. Access to hard copies of this and other materials he collected can be requested from the Melanesian Studies Resource Center at the University of California, San Diego.