Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach y, sach ty
va lang » va nang, hoa lang
va hang » van hang, va nang, va hanh
tu sach » thu sach, su sach, te sach
nam luc » nang luc, nhan luc, nam duoc
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
co tren » cu tren, do tren, ca tren
doi co » doi bo, moi co, hoi co

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

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