Conklin, Harold C., Pugguwon Lupaih, Miklos Pinther, and the American Geographical Society of New York. (1980).  American Geographical Society of New York (ed.). Ethnographic Atlas of Ifugao: A Study of Environment, Culture, and Society in Northern Luzon. Yale University Press. ISBNxa00-300-02529-7.CS1 maint: multiple names: authors list (link)