Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
nam duoc » nam thuoc, da duoc, dat duoc
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hang di » hang doi, hang vi, hang dien
va hang » van hang, va nang, va lang
cu tren » tu tren, dua tren
nam luc » nang luc, nhan luc, nam luat
hieu va » lieu va, hieu qua
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
di cu » di cau, di cua, di du

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 va ((((nam luc) OR (nam duoc))) OR (nam thuc)) va hang di cu tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky tang xa hoi. hieu va ((((nam luc) OR (nam duoc))) or (nam thuc)) va hang di cu tren~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky tang xa hoi. hieu va ((((nam luc) OR (nam duoc))) or (nam thuc)) va hang di cu tren*.