Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van nang » van quang, van ban, van dong
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
cam luc » cam xuc, cau luc
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cac, va cao
v nang » va nang, vu nang, voi nang
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 ((v nang) or (van nang)) xa hoi. hieu va cam luc ((va hanh) OR (va danh)) de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((v nang) OR (van nang)) xa hoi. hieu va cam luc ((va hanh) OR (va danh)) de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((v nang) or (van nang)) xa hoi. hieu va cam luc ((va hanh) OR (va danh)) de cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((v nang) or (van nang)) xa hoi. hieu va cam luc ((va hanh) OR (va danh)) de cua tre*.