Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh vai » hanh vi, hanh va, hanh tai
van hanh » van thanh, ban hanh, van anh
sach ty » sach y, sach tu, sach thu
cuu tre » cua tre, cau tren, cau treo
tu truc » tu thuoc, tu trung
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
ma hoi » mai hoi, xa hoi, ma hoa
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ty nang ma hoi. hieu qua ((tu truc) or (cau truc)) van hanh vai ((cua te) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty nang ma hoi. hieu qua ((tu truc) OR (cau truc)) van hanh vai ((cua te) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: toc sach ty nang ma hoi. hieu qua ((tu truc) or (cau truc)) van hanh vai ((cua te) or (cuu tre))*.