Letter from Penghulu Bungan Arong to Lim Chan Koon on research on edible birdsnest at their cave in Lubang Beruang, Sg. Kejin, Baram

Letter from Penghulu Bungan Arong to the 5th Earl of Cranbrook thanking him for including her caves in Middle Baram in the research project

Letter from Peter F. Burgess to the 5th Earl of Cranbrook concerning the 1959 survey on swiftlet nests

Letter from Peter F. Burgess to the 5th Earl of Cranbrook indorming him that he (Burgess) had obtained four skins of swiftlets from Segarong and would like to send them to him

Letter from Peter F. Burgess to the 5th Earl of Cranbrook indorming him that the skins of swiftlets sent to Kuching were from Baturong Caves rather than from Segarong

Letter from Peter F. Burgess to the 5th Earl of Cranbrook on Collocalia skins from Sandakan, Sabah

Letter from Peter Hogg to the 5th Earl of Cranbrook on request for reprints for Mrs J. F. M. Horne of Kenya

Letter from Peter Hollander to J. K. Clark concerning repaying mailing expenses

Letter from Peter Hollander to the 5th Earl of Cranbrook concerning swiftlets as sibling species

Letter from Peter Hollander to the 5th Earl of Cranbrook on the heads of Collocalia esculenta which he had received. He also mentioned of trying to get heads of Collocalia maxima. He also asked if there were facilities for visiting students in Malaysia and if electrophysiological work was possible