Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ban hanh » ban hang
lang hai » lang chai, lang thai, lang ha
cham hoc » cham soc, chat hoc, cham hoi
va cham » va chat, va tham
hanh de » hanh ve, hanh kem
hoc ban » hoc bang, hoc dan, hoc bai
hieu va » lieu va, hieu qua
hai hoi » dai hoi, hai moi, hai hai
ky lang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
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: ((te sach) or (toc sach)) ky lang hai hoi. hieu va cham hoc ban hanh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky lang hai hoi. hieu va cham hoc ban hanh de cua tre.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ky lang hai hoi. hieu va cham hoc ban hanh de cua tre*.