Perhaps you should try some spelling variations:
dung tren » dung trong, dung trung
nam thuc » nam thuoc, am thuc, nam thu
nhan luc » nang luc
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
tang xa » trang xa, tang ma, lang xa
sach ky » sac ky, sach y, sach ty
ky tang » ky nang, ky dang, kho tang
va hang » van hang, va nang, va lang
hang di » hang doi, hang vi, hang dien
cu tren » tu tren, dua tren

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky tang xa hoi. hieu van ((nhan luc) or (nam thuc)) va hang di ((cu tren) or (dung tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky tang xa hoi. hieu van ((nhan luc) OR (nam thuc)) va hang di ((cu tren) OR (dung tren)).
• Adding a wildcard symbol may retrieve word variants: thu sach ky tang xa hoi. hieu van ((nhan luc) or (nam thuc)) va hang di ((cu tren) or (dung tren))*.