Perhaps you should try some spelling variations:
vanh dai » van dai, vanh tai, lanh dao
su sach » vu sach
so sach » so sanh, bo sach, co sach
ky lang » ky nang, ky dang, tay lang
ky tang » ky nang, ky dang, kho tang
qua hai » qua hoat
hai duc » hoai duc, mai duc, ha duc
va vanh » va van, va danh, va hanh
cua cu » cua chu, cua cau, cua 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) OR (so sach)) ((ky lang) or (ky tang)) xa hoi. hieu qua hai duc va vanh dai cua cu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) ((ky lang) OR (ky tang)) xa hoi. hieu qua hai duc va vanh dai cua cu*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (so sach)) ((ky lang) or (ky tang)) xa hoi. hieu qua hai duc va vanh dai cua cu*".