The Routledge Encyclopedia of Taoism (2 vols.) by 
Encyclopedia of Chinese Philosophy by 
Encyclopedia of Asian Philosophy by 
Companion Encyclopedia of Asian Philosophy by 
Daoism Handbook (2 vols.) by Begin with the pattern established by Library of Congress Subject Headings on Christianity & Hinduism, consulting Library of Congress Subject Headings as you go.
Begin with the pattern established by Atla Religion Database Subject Headings on Christianity & Hinduism, consulting the Atla Religion Database's Thesaurus as you go.
