Perhaps you should try some spelling variations:
hieu nganh » vien nganh, hiem ngan, hieu manh
thanh tinh » thanh binh, nhanh tinh, than kinh
hanh tinh » hanh trinh, nhanh tinh, canh tinh
tong cong » trong cong, cong cong, dung cong
doc hieu » toc thieu, hoc thieu, hoc hien
cong dan » cong san, cong tan, huong dan
dan than » dan chan, ban than, van than
than tap » toan tap, han tap, phan tap
he tong » he thong, he trong, he cong

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 nganh - ((hanh tinh) or (thanh tinh)) he tong cong dan than tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu nganh - ((hanh tinh) OR (thanh tinh)) he tong cong dan than tap.
• Adding a wildcard symbol may retrieve word variants: doc hieu nganh - ((hanh tinh) or (thanh tinh)) he tong cong dan than tap*.