Perhaps you should try some spelling variations:
thanh hang » thanh hoang, thanh thang, tranh hang
hieu tinh » chieu tinh, lieu tinh, hieu binh
kieu tinh » lieu tinh, trieu tinh, diep tinh
khoan cam » khoa cam, khoan va, phan cam
cong dan » cong san, huong dan, cong dong
cong tan » cong tac, cong san, cong thanh
va dung » van dung, va duong, vat dung

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu tinh) or (kieu tinh)) - thanh hang va dung ((cong dan) OR (cong tan)) khoan cam~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu tinh) OR (kieu tinh)) - thanh hang va dung ((cong dan) OR (cong tan)) khoan cam.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu tinh) or (kieu tinh)) - thanh hang va dung ((cong dan) OR (cong tan)) khoan cam".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu tinh) or (kieu tinh)) - thanh hang va dung ((cong dan) OR (cong tan)) khoan cam*.