Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
hang doi » hang di, hang loi, huong doi
hieu van » hieu va, thien van, hieu ve
tu sach » thu sach, su sach, te sach
va hang » van hang, va nang, va lang
nam luc » nang luc, nhan luc, nam duoc
sach ky » sac ky, sach y, sach ty
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
cu tren » tu tren, dua tren
doi cu » doi cua, doi co, doi ca

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky tang xa hoi. ((hieu van) OR (lieu va)) ((nam luc) OR (nam thuc)) va hang doi cu tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky tang xa hoi. ((hieu van) OR (lieu va)) ((nam luc) or (nam thuc)) va hang doi cu tren~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky tang xa hoi. ((hieu van) OR (lieu va)) ((nam luc) or (nam thuc)) va hang doi cu tren*.