Perhaps you should try some spelling variations:
hoang van » hang va
sanh thu » sach thu, san thu, doanh thu
tang van » dang van, trong van, tang luan
so sanh » do sanh
duy van » duy vat, dung van
va pham » van pham, va phat, va phap
hieu va » lieu va, hieu qua
duy va » duy vat, day va, duy v
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 sanh thu ((tang van) or (hoang van)) hoi. hieu va pham ((duy va) OR (duy van)) hanh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sanh thu ((tang van) OR (hoang van)) hoi. hieu va pham ((duy va) OR (duy van)) hanh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sanh thu ((tang van) or (hoang van)) hoi. hieu va pham ((duy va) OR (duy van)) hanh vi cua te".
• Adding a wildcard symbol may retrieve word variants: so sanh thu ((tang van) or (hoang van)) hoi. hieu va pham ((duy va) OR (duy van)) hanh vi cua te*.