Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
lang van » dang van, tang van, hoang van
hanh di » hanh de, hang di, danh di
cac tac » cac toc, cac bac, cac dac
qua cac » cua cac
van hoi » van hoa, van hoc, van hoe
cua tre » cua te, cuu tre, cua triet
v lang » va lang, o lang, _ lang
tac va » tac da, tac xa, tuc va

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) OR (hoc sach)) v lang van hoi. hieu qua cac tac va ((hanh di) or (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) v lang van hoi. hieu qua cac tac va ((hanh di) OR (hanh vi)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (hoc sach)) v lang van hoi. hieu qua cac tac va ((hanh di) or (hanh vi)) cua tre*".