Perhaps you should try some spelling variations:
hoang van » hang va
tang luan » dung luan
sach thu » sach thue, sach thieu, sach tham
van hanh » van thanh, ban hanh, van anh
so sach » so sanh, bo sach, co sach
va hanh » va thanh, va danh, ban hanh
cam tuc » cam xuc, cam tu, nam thuc
hieu va » lieu va, hieu qua
va cam » va cham, va cac, va cao
vi cua » vai cua, di cua
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach thu ((tang luan) or (hoang van)) hoi. hieu va cam tuc ((va hanh) OR (van hanh)) vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach thu ((tang luan) OR (hoang van)) hoi. hieu va cam tuc ((va hanh) OR (van hanh)) vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach thu ((tang luan) or (hoang van)) hoi. hieu va cam tuc ((va hanh) OR (van hanh)) vi cua te".
• Adding a wildcard symbol may retrieve word variants: so sach thu ((tang luan) or (hoang van)) hoi. hieu va cam tuc ((va hanh) OR (van hanh)) vi cua te*.