^Obo at Ethnologue (18th ed., 2015) (subscription required)
^Brainard, Sherri; Vander Molen, Ena (2005). Word order inverse in Obo Manobo. In Hsiu-chuan Liao and Carl R. Galvez Rubino (eds.), Current issues in Philippine linguistics and anthropology: Parangal kay Lawrence A. Reid: Manila: Linguistic Society of the Philippines and SIL Philippines. pp. 364–418.{{cite book}}: CS1 maint: publisher location (link)