Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
van hai » van ha, van chat, van hanh
hang di » hang doi, hang vi, hang dien
cua tre » cua te, cuu tre, cua triet
hai du » hai vu, tai du, hai di
du van » duy van, duc van, tu van

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ty nang x ho. hieu van hai du van ((hang di) or (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty nang x ho. hieu van hai du van ((hang di) OR (hanh vi)) cua tre.
• Adding a wildcard symbol may retrieve word variants: thu sach ty nang x ho. hieu van hai du van ((hang di) or (hanh vi)) cua tre*.