Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cau thuc » cau truc, can thuc, cau phuc
cuu thuc » cuu tac
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
va hanh » van hanh, va thanh, va danh
hanh ha » nhanh ha, thanh ha, hanh hoa
cua tre » cua te, cuu tre, cua triet
ha cua » hoa cua, hai cua, nha cua

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 (toc sach)) ky nang ma hoa. hieu qua ((cau thuc) or (cuu thuc)) va hanh ha cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (toc sach)) ky nang ma hoa. hieu qua ((cau thuc) OR (cuu thuc)) va hanh ha cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (toc sach)) ky nang ma hoa. hieu qua ((cau thuc) or (cuu thuc)) va hanh ha cua tre*.