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 hang » van hang, va nang, va lang
su sach » so sach, vu sach
nam luc » nang luc, nhan luc, nam duoc
nang xa » nang x, lang xa, nang ma
di cu » di cau, di cua, di du
li du » ly du

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 ky nang xa hoi. hieu van ((nam luc) or (nam thuc)) va hang ((di cu) or (li du)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang xa hoi. hieu van ((nam luc) OR (nam thuc)) va hang ((di cu) OR (li du)) tren.
• Adding a wildcard symbol may retrieve word variants: su sach ky nang xa hoi. hieu van ((nam luc) or (nam thuc)) va hang ((di cu) or (li du)) tren*.