Perhaps you should try some spelling variations:
nuoc sach » nguoi sach, hoc sach, cuoc cach
toc sach » hoc sach, doc sach, thuoc sach
cua tre » cua te, cua triet, dua tren
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
cam luc » cam xuc, cau luc
hieu va » lieu va, hieu qua
cuu tre » cau tren, cau treo
va nang » van nang, da nang, cam nang
nang o » nang co, nang ho, nang ro
luc va » duc va, tuc va, loc va
va cam » va cham, va cac, va cao
o hoi » co hoi, o hoc, o hai

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