Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
va hanh » van hanh, va thanh, va danh
nang xa » nang x, lang xa, nang ma
va nang » van nang, da nang, cam nang
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cao, va cai
luc va » duc va, tuc va, loc va
vi cua » vai cua, di 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 (doc sach)) va nang xa hoi. hieu ((va cam) OR (va cac)) luc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) va nang xa hoi. hieu ((va cam) OR (va cac)) luc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (doc sach)) va nang xa hoi. hieu ((va cam) OR (va cac)) luc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) va nang xa hoi. hieu ((va cam) OR (va cac)) luc va hanh vi cua tre*.