Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
van hanh » van thanh, ban hanh, van anh
nhan luc » nang luc
hieu van » hieu va, thien van, lieu va
hau luc » hau loc, cau luc, hieu luc
hanh de » hanh ve, hanh kem
nang ma » tang ma, sang ma, nang cao
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) OR (hoc 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) OR (hoc sach)) ky nang ma hoi. hieu van ((hau luc) OR (nhan luc)) van hanh de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (hoc 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) OR (hoc sach)) ky nang ma hoi. hieu van ((hau luc) or (nhan luc)) van hanh de cua tre*.