Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dang xay » dang van, van xay
hanh di » hanh de, hang di, danh di
cam luc » cam xuc, cau luc
hieu va » lieu va, hieu qua
lang xa » lang ha, lang van
cua tre » cua te, cuu tre, cua triet
sach v » sach va, sach y, sach 2
va cam » va cham, va cac, va cao
luc va » duc va, tuc va, loc 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 v ((lang xa) OR (dang xay)) hoi. hieu va cam luc va ((hanh di) or (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach v ((lang xa) OR (dang xay)) hoi. hieu va cam luc va ((hanh di) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach v ((lang xa) OR (dang xay)) hoi. hieu va cam luc va ((hanh di) or (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach v ((lang xa) OR (dang xay)) hoi. hieu va cam luc va ((hanh di) or (hanh vi)) cua tre*.