Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » thien van, lieu va
tay dang » tay dong, tay dung, tay lang
dang van » hoang van, hang va
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
cam thuc » am thuc, nam thuc, cam thu
sach tay » xach tay, sach hay, sach nay
hieu va » lieu va, hieu qua
van hoi » van hoa, van hoc, van hoe
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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 tay dang van hoi. ((((hieu ve) OR (hieu va))) or (hieu van)) cam thuc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach tay dang van hoi. ((((hieu ve) OR (hieu va))) OR (hieu van)) cam thuc van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach tay dang van hoi. ((((hieu ve) OR (hieu va))) or (hieu van)) cam thuc van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach tay dang van hoi. ((((hieu ve) OR (hieu va))) or (hieu van)) cam thuc van hanh vi cua tre*.