Perhaps you should try some spelling variations:
hieu xanh » chieu xanh, hieu manh, hieu nganh
tong cong » trong cong, cong cong, dung cong
pham toan » pham tuan, pham tan, phap toan
doc hieu » toc thieu, hoc thieu, hoc hien
manh cua » doanh cua
tac toan » tap toan, tam toan, hach toan
ban cua » ban quan

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 - canh ((manh cua) or (ban cua)) tong cong ((tac toan) or (pham toan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu xanh - canh ((manh cua) OR (ban cua)) tong cong ((tac toan) OR (pham toan)) cau.
• Adding a wildcard symbol may retrieve word variants: doc hieu xanh - canh ((manh cua) or (ban cua)) tong cong ((tac toan) or (pham toan)) cau*.