Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
lang van » dang van, hoang van, giang van
tang van » dang van, hoang van, trong van
hieu ve » hieu va, hieu van
tuc van » thuc van, truc van, duc van
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, ve cac, va cam
tuc va » thuc va, truc va, tuc xa
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 van) OR (tang van)) hoi. hieu ve cam ((tuc van) or (tuc va)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((lang van) OR (tang van)) hoi. hieu ve cam ((tuc van) OR (tuc va)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y ((lang van) OR (tang van)) hoi. hieu ve cam ((tuc van) or (tuc va)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach y ((lang van) OR (tang van)) hoi. hieu ve cam ((tuc van) or (tuc va)) hanh vi cua tre*.