Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
cac luc » cau luc, cac nuoc, cac cuoc
hanh di » hanh de, hang di, danh di
cua tre » cua te, cuu tre, cua triet
sach o » sach lo, sac o, sach y
o lang » hoa lang, hoi lang

You may be able to get more results by adjusting your search query.

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