Perhaps you should try some spelling variations:
thong cong » trong cong, tong cong, thong thong
hieu xanh » chieu xanh, hieu manh, hieu nganh
trong van » trong cac
doc hieu » toc thieu, hoc thieu, hoc hien
tang van » dang van, hoang van, tang luan
cong dan » cong san, cong tan, huong dan
than tap » han tap, phan tap, than cap
toan tap » toan ban

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 xanh - hanh ((tang van) or (trong van)) thong cong dan ((than tap) OR (toan tap))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu xanh - hanh ((tang van) OR (trong van)) thong cong dan ((than tap) OR (toan tap)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu xanh - hanh ((tang van) or (trong van)) thong cong dan ((than tap) OR (toan tap))".
• Adding a wildcard symbol may retrieve word variants: doc hieu xanh - hanh ((tang van) or (trong van)) thong cong dan ((than tap) OR (toan tap))*.