Perhaps you should try some spelling variations:
nang cai » nang cao, nang tai, nang cap
cham duc » pham duc, pham duy, phan duc
hang vai » hang tai, hang hai, hang vi
su triet » su viet, su tien, ve triet
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cai hoi » cau hoi, dai hoi, cai hoa
hieu ve » hieu va, hieu van

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 hoi. hieu ve ((cham duc) OR (cham soc)) va ((hang vai) or (hang va)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang cai hoi. hieu ve ((cham duc) OR (cham soc)) va ((hang vai) OR (hang va)) su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang cai hoi. hieu ve ((cham duc) OR (cham soc)) va ((hang vai) or (hang va)) su triet".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang cai hoi. hieu ve ((cham duc) OR (cham soc)) va ((hang vai) or (hang va)) su triet*.