Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
cau luc » cau truc, cau phuc
cam luc » cam xuc
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
da nang » cam nang, kha nang, cao nang
nang o » nang co, nang ho, nang ro
di cua » dai cua, doi cua, de cua
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 (hoc sach)) da nang o hoi. hieu va ((cam luc) OR (cau luc)) va hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) da nang o hoi. hieu va ((cam luc) OR (cau luc)) va hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) da nang o hoi. hieu va ((cam luc) OR (cau luc)) va hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sach)) da nang o hoi. hieu va ((cam luc) OR (cau luc)) va hanh di cua tre*.