Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
qua cham » qua hai, qua cac, va cham
cham luc » cham soc, nhan luc, cham cuu
doc sach » hoc sach, nuoc sach, dac sac
va nang » van nang, da nang, cam nang
nang xa » nang x, lang xa, nang ma
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
luc va » duc va, tuc va, loc va

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 (doc sach)) va nang xa hoi. hieu qua cham 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 (doc sach)) va nang xa hoi. hieu qua cham luc va hanh di ((cua tre) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) va nang xa hoi. hieu qua cham luc va hanh di ((cua tre) or (cuu tre))*.