Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
nam truc » nam truoc, nam thuc, nam trung
va thanh » gia thanh, ban thanh, va tinh
ban hanh » ban hang
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa

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 y nang ma hoi. hieu van nam truc ((va thanh) or (ban hanh)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang ma hoi. hieu van nam truc ((va thanh) OR (ban hanh)) dai cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach y nang ma hoi. hieu van nam truc ((va thanh) or (ban hanh)) dai cua tre*.