Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va thanh » gia thanh, ban thanh, va tinh
sach vu » sach va, sach tu, sach uu
va hanh » van hanh, va danh, ban hanh
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, nang ma
vu nang » vuc nang, va nang, vu dang
va cam » va cham, va cao, va cai
de cua » le cua, te cua, dieu 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 vu nang xa hoi. hieu ((va cam) OR (va cac)) luc ((va hanh) or (va thanh)) de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach vu nang xa hoi. hieu ((va cam) OR (va cac)) luc ((va hanh) OR (va thanh)) de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach vu nang xa hoi. hieu ((va cam) OR (va cac)) luc ((va hanh) or (va thanh)) de cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach vu nang xa hoi. hieu ((va cam) OR (va cac)) luc ((va hanh) or (va thanh)) de cua tre*.