Perhaps you should try some spelling variations:
nam trung » nam trong, tai trung, ba trung
va trien » va truyen, va thiet, va tuyen
hanh vai » hanh vi, hanh va, hanh tai
nam truc » nam truoc, nam thuc, nam thuoc
cam truc » cau truc, lam truoc, nam truoc
va hanh » van hanh, va thanh, va danh
su sach » so sach, vu sach
sach vu » sach va, sach tu, sach uu
nang ma » tang ma, sang ma, nang cao
vu nang » vuc nang, va nang, vu dang
ma hoi » mai hoi, xa hoi, ma hoa
vai va » mai va, dai va, hai va

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 vu nang ma hoi. hieu qua ((((cam truc) or (nam trung))) or (nam truc)) va hanh vai va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach vu nang ma hoi. hieu qua ((((cam truc) OR (nam trung))) OR (nam truc)) va hanh vai va trien.
• Adding a wildcard symbol may retrieve word variants: su sach vu nang ma hoi. hieu qua ((((cam truc) or (nam trung))) or (nam truc)) va hanh vai va trien*.