Perhaps you should try some spelling variations:
nang cai » nang tai, nang cap, nang can
danh vai » danh sai, danh va, doanh van
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cam duc » cam xuc, cao duc, pham duc
va danh » va dinh, va dan, va hanh
ve cam » ve cham, ve cac, va cam
vai va » mai va, dai va, hai 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: su sach ky ((nang cai) or (nang cao)) hoi. hieu ve cam duc va danh vai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang cai) OR (nang cao)) hoi. hieu ve cam duc va danh vai va thiet.
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang cai) or (nang cao)) hoi. hieu ve cam duc va danh vai va thiet*.