Written by American anthropologists/ethnologists:
A.R. Krober's Peoples of the Philippines (1943)
https://archive.org/details/philipp00kroe/mode/2up
Fay-Cooper Cole's The Wild Tribe of Davao District, Mindanao (1913)
https://archive.org/details/jstor-29782138/page/n2/mode/2up
David Barrow's A History of the Philippines (1905)
https://archive.org/details/historyofphilipp00barriala/page/n8/mode/2up
Ano pa ba?