ETS's Classification System on Field
Google Schoolar Search Subject Areas
CNKI: Journal, Conference, Newspaper, Yearbook, Encyclopedia, Dictionary, Statistics, Patent, Standard, etc.
西学-孙中山
Reference type - iTunes: Apps, Books, Movies, Podcasts, TV Shows, iTunes U.
Refernece type - Zotero (English)
Refernece type - Zotero(中文):
Citation type (Chinese)
kat.ph: Book | Game | Movie | Music | Software(Apps) | TV-Shows(Plays) | Video
Usenet Classification & Category, Philosophy
Yahoo Internet Catalog
Apply Wikipedia's taxonomy to classify IMAGE (Picture, Photo) (Category from Wikipeida)
Apply 500px's taxonomy to classify IMAGE