Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
tay lang » tai lang, tay tang, tay quang
hieu va » lieu va, hieu qua
tuc van » thuc van, truc van, tuc va
cam tuc » cam xuc, cam tu, nam thuc
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu van
van hoi » van hoa, van hoc, van hoe
y lang » o lang, _ lang, yen lang
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 ((y lang) or (tay lang)) van hoi. ((hieu ve) OR (hieu va)) cam tuc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((y lang) OR (tay lang)) van hoi. ((hieu ve) OR (hieu va)) cam tuc van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((y lang) or (tay lang)) van hoi. ((hieu ve) OR (hieu va)) cam tuc van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((y lang) or (tay lang)) van hoi. ((hieu ve) OR (hieu va)) cam tuc van hanh vi cua tre*.