Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach tu » sach thu, cach tu, sach ty
tu nang » tru nang, tu nong, tu nano
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cao thi » cau thi, cao tai, dao thi
va hang » van hang, va lang, va hanh
va nang » van nang, da nang, cam nang
va cao » va cac, va co, va dao
tai su » tai so, tai tu, lai su

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 tu nang xa hoi. hieu va cao thi ((va hang) or (va nang)) tai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu nang xa hoi. hieu va cao thi ((va hang) OR (va nang)) tai su triet.
• Adding a wildcard symbol may retrieve word variants: tu sach tu nang xa hoi. hieu va cao thi ((va hang) or (va nang)) tai su triet*.