Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh dai » hanh tai, hanh dao, vanh dai
va hanh » van hanh, va thanh, va danh
cam luc » cau luc
hieu va » lieu va, hieu qua
nang ho » nang hoc, nang co, tang ho
va nang » van nang, da nang, cam nang
cua tre » cua te, cuu tre, cua triet
ho hoi » hoc hoi, hoa hoi, hoi hoi

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