Perhaps you should try some spelling variations:
hieu cach » hieu cac, chieu sach, hieu ca
hanh tang » hanh trang, anh tang, hanh mang
tang luan » dung luan
bang cong » bang song, hang cong, dung cong
dang cong » dung cong
hoc hieu » hoc thieu, hoc hien, doc hieu
dan than » dan chan, ban than, van than
than cau » toan cau, phan cau, than cap

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu cach - hanh tang luan ((bang cong) or (dang cong)) dan than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu cach - hanh tang luan ((bang cong) OR (dang cong)) dan than cau.
• Adding a wildcard symbol may retrieve word variants: hoc hieu cach - hanh tang luan ((bang cong) or (dang cong)) dan than cau*.