Perhaps you should try some spelling variations:
vien dai » hien dai
su triet » su tien, ve triet
vien dat » vien da, viec dat, mien dat
ban hang » ngan hang
nuoc ban » nuoc san, quoc ban, buoc ban
hang vi » hang va, hanh vi, hang di
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
su viet » so viet

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 tang xa hoi. hieu ((vien dat) or (vien dai)) nuoc ban hang vi ((su triet) or (su viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky tang xa hoi. hieu ((vien dat) OR (vien dai)) nuoc ban hang vi ((su triet) OR (su viet)).
• Adding a wildcard symbol may retrieve word variants: su sach ky tang xa hoi. hieu ((vien dat) or (vien dai)) nuoc ban hang vi ((su triet) or (su viet))*.