Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
ty nang » ky nang, ty xang, ty hang
mai hoi » mai khoi, dai hoi, lai hoi
van dau » van dao, phan dau
dau tuc » dau tu, dao tuc, cau truc
anh tai » hanh tai, anh thai, vanh tai
tuc va » thuc va, truc va, tuc xa
va anh » van anh, va danh, va hanh
tai va » thai va, mai va, tri va
thiet » thieu

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) or (su sach)) ty nang mai hoi. hieu van dau tuc va anh tai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ty nang mai hoi. hieu van dau tuc va anh tai va thiet.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ty nang mai hoi. hieu van dau tuc va anh tai va thiet*.