Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
nhan luc » nang luc
van hanh » van thanh, ban hanh, van anh
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
hau luc » hau loc, cau luc, hieu luc
hanh de » hanh ve, hanh kem
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
de cua » le cua, te cua, dieu cua

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 ky nang ma hoi. hieu van ((hau luc) or (nhan luc)) van hanh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang ma hoi. hieu van ((hau luc) OR (nhan luc)) van hanh de cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang ma hoi. hieu van ((hau luc) or (nhan luc)) van hanh de cua tre*.