Perhaps you should try some spelling variations:
thanh luc » thanh luu, than luc, nhan luc
hanh tai » thanh tai, hang tai, han tai
hieu van » thien van, lieu va, hieu ve
su sach » so sach, vu sach
tai cua » thai cua, tai cuc, tri cua
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
luc va » duc va, tuc va, loc va
ma hoi » mai hoi, xa hoi, ma hoa
_ sang » _ san
v sang » va sang, ve sang, van sang
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: su sach ((v sang) OR (_ sang)) ma hoi. ((hieu van) or (hieu va)) thanh luc va hanh tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((v sang) OR (_ sang)) ma hoi. ((hieu van) OR (hieu va)) thanh luc va hanh tai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((v sang) OR (_ sang)) ma hoi. ((hieu van) or (hieu va)) thanh luc va hanh tai cua te".
• Adding a wildcard symbol may retrieve word variants: su sach ((v sang) OR (_ sang)) ma hoi. ((hieu van) or (hieu va)) thanh luc va hanh tai cua te*.