Perhaps you should try some spelling variations:
luong cong » dung cong, trong cong, cong cong
hieu cach » chieu sach, hieu ca, biet cach
cong manh » cong danh, duong manh, cong thanh
manh toan » thanh toan, anh tuan, tinh toan
hieu cac » hieu luc, hieu va, hieu van
tang mau » trang mau, dang mau, thanh mau
toan ban » van ban
tang ma » mang may, tang van

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

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu cach) OR (hieu cac)) - hanh ((tang mau) OR (tang ma)) luong cong manh toan ban~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu cach) OR (hieu cac)) - hanh ((tang mau) or (tang ma)) luong cong manh toan ban~".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu cach) OR (hieu cac)) - hanh ((tang mau) or (tang ma)) luong cong manh toan ban*.