Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
van hanh » van thanh, ban hanh, van anh
hanh di » hanh vi, hanh de, hang di
luc van » luoc van, luu van, duc van
cam luc » cam xuc, cau luc
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
nang ro » nang co, nang ho, nang ra
va cam » va cham, va cac, va cao
nang o » nang co, nang ho, nang x
di cua » dai cua, doi cua, de cua

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)) va ((nang o) or (nang ro)) hoi. hieu va cam luc van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) va ((nang o) OR (nang ro)) hoi. hieu va cam luc van hanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sach)) va ((nang o) or (nang ro)) hoi. hieu va cam luc van hanh di cua tre*.