Perhaps you should try some spelling variations:
vu khach » vu khanh, vu khac, vay khach
ban duoc » tan duoc, van duoc, ban thuoc
duoc hoi » quoc hoi, duoc hoc, duoc si
va triet » va thiet, va trien, ve triet
su sach » so sach, vu sach
cao tuc » dao tuc, cao duc, cao suc
danh va » doanh va, hanh va, dan va
tuc va » thuc va, truc va, tuc xa
anh va » hanh va
va cao » va cac, va co, va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((vu khach) or (su sach)) van ban duoc hoi. lieu va cao tuc va ((danh va) OR (anh va)) va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu khach) OR (su sach)) van ban duoc hoi. lieu va cao tuc va ((danh va) OR (anh va)) va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((vu khach) or (su sach)) van ban duoc hoi. lieu va cao tuc va ((danh va) OR (anh va)) va triet".
• Adding a wildcard symbol may retrieve word variants: ((vu khach) or (su sach)) van ban duoc hoi. lieu va cao tuc va ((danh va) OR (anh va)) va triet*.