Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
trong van » trong cac
tang van » dang van, hoang van, tang luan
hieu va » lieu va, hieu qua
cac luc » cau luc, coc luc, cac nuoc
va tinh » may tinh
cau tre » cau tren, cau treo, cau tra
su sac » su sach, su cac, su xac
sac ky » cac ky, sai ky
va cau » van cau, va dau, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sac ky ((tang van) or (trong van)) hoc. hieu va cac luc ((va tinh) or (ban thanh)) va cau tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sac ky ((tang van) OR (trong van)) hoc. hieu va cac luc ((va tinh) OR (ban thanh)) va cau tre.
• Adding a wildcard symbol may retrieve word variants: su sac ky ((tang van) or (trong van)) hoc. hieu va cac luc ((va tinh) or (ban thanh)) va cau tre*.