Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
hieu van » hieu va, thien van, lieu va
lam thuc » lam thuoc, nam thuc, dam thuc
hanh dai » hanh tai, hanh dao, vanh dai
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
va hanh » van hanh, va thanh, va danh
ma hoi » mai hoi, xa hoi, ma hoa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (thuoc sach)) ky nang ma hoi. hieu van ((lam thuc) OR (am thuc)) va hanh dai cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thuoc sach)) ky nang ma hoi. hieu van ((lam thuc) OR (am thuc)) va hanh dai cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thuoc sach)) ky nang ma hoi. hieu van ((lam thuc) OR (am thuc)) va hanh dai cua vat".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thuoc sach)) ky nang ma hoi. hieu van ((lam thuc) OR (am thuc)) va hanh dai cua vat*.