Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
hieu van » hieu va, thien van, lieu va
hang di » hang doi, hang vi, hang dien
van hac » van hoc, van ha, van hai
ty nang » ky nang, ty xang, ty hang
tu sach » su sach, te sach, tu cach
cua tre » cua te, cuu tre, cua triet
hac du » cac du, han du, hac de
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) OR (tu sach)) ty nang x ho. hieu van hac du van ((hang di) or (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (tu sach)) ty nang x ho. hieu van hac du van ((hang di) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) OR (tu sach)) ty nang x ho. hieu van hac du van ((hang di) or (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) OR (tu sach)) ty nang x ho. hieu van hac du van ((hang di) or (hanh vi)) cua tre*.