Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
hanh lai » hanh lam, hanh tai, thanh lap
hieu van » hieu va, thien van, lieu va
thuc va » thuc vat, thuc dan, thuc day
su sach » so sach, vu sach
van cam » van nam, van lam, van cau
tuc va » truc va, tuc xa, duc va
lai va » loai va, mai va, dai va

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ((thi hanh) OR (thi thanh)) xa hoi. hieu van cam ((tuc va) or (thuc va)) hanh lai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((thi hanh) OR (thi thanh)) xa hoi. hieu van cam ((tuc va) OR (thuc va)) hanh lai va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((thi hanh) OR (thi thanh)) xa hoi. hieu van cam ((tuc va) or (thuc va)) hanh lai va triet".
• Adding a wildcard symbol may retrieve word variants: su sach ((thi hanh) OR (thi thanh)) xa hoi. hieu van cam ((tuc va) or (thuc va)) hanh lai va triet*.