Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
thi van » thi lan, thi hanh, thi nang
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
sach ky » sac ky, sach y, sach ty
su sach » so sach, vu sach
oi su » ki su
vi su » va su, ve su, ki su

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. thi van nam thuc ((ban hang) OR (ngan hang)) ((oi su) or (vi su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky tang xa hoi. thi van nam thuc ((ban hang) OR (ngan hang)) ((oi su) OR (vi su)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky tang xa hoi. thi van nam thuc ((ban hang) OR (ngan hang)) ((oi su) or (vi su)) triet".
• Adding a wildcard symbol may retrieve word variants: su sach ky tang xa hoi. thi van nam thuc ((ban hang) OR (ngan hang)) ((oi su) or (vi su)) triet*.