Perhaps you should try some spelling variations:
chi xanh » chi anh, chi danh, chi hanh
tung hoc » trung hoc, tuong hoc, tung ho
dung hoc » dong hoc, dung thuoc, trung hoc
cong tap » cuong tap, cong tac, tong tap
cong tan » cong tac, cong san, cong thanh
toan cau » toan cao, toan ban, toan tap
doi chi » doi khi

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doi chi xanh - thanh ((tung hoc) or (dung hoc)) thuong ((cong tap) OR (cong tan)) toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi chi xanh - thanh ((tung hoc) OR (dung hoc)) thuong ((cong tap) OR (cong tan)) toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi chi xanh - thanh ((tung hoc) or (dung hoc)) thuong ((cong tap) OR (cong tan)) toan cau".
• Adding a wildcard symbol may retrieve word variants: doi chi xanh - thanh ((tung hoc) or (dung hoc)) thuong ((cong tap) OR (cong tan)) toan cau*.