Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
hanh hai » thanh hai, nhanh hai, hang hai
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
van cac » van hac, van cau, van bac
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet

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 xa hoi. hieu van cac ((duc ton) or (duc tan)) hanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang xa hoi. hieu van cac ((duc ton) OR (duc tan)) hanh hai cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang xa hoi. hieu van cac ((duc ton) or (duc tan)) hanh hai cua tre*.