Perhaps you should try some spelling variations:
hieu nganh » vien nganh, hiem ngan, hieu manh
chieu sach » chinh sach, chiet tach, chieu sang
hinh tinh » hinh dinh, hinh kinh, hinh minh
tong tan » trong tan, cong tan, tong tap
toan ban » van ban
tinh va » tich va, trinh van, trinh vat
va han » va phan, van han, va hanh

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi ((hieu nganh) or (chieu sach)) - hinh tinh va han tong tan ((toan tap) or (toan ban))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi ((hieu nganh) OR (chieu sach)) - hinh tinh va han tong tan ((toan tap) OR (toan ban)).
• Adding a wildcard symbol may retrieve word variants: doi ((hieu nganh) or (chieu sach)) - hinh tinh va han tong tan ((toan tap) or (toan ban))*.