Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
vu nang » vuc nang, va nang, vu dang
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cao luc » bao luc, cao duc, cao suc
va danh » va dinh, va dan, va hanh
luc va » duc va, tuc va, loc va
di cua » dai cua, doi cua, de cua
va cao » va cac, va co, va dao
di ca » di cau, doi ca, li ca

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) vu nang xa hoi. hieu va cao luc va danh ((di ca) OR (di cua)) tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) vu nang xa hoi. hieu va cao luc va danh ((di ca) OR (di cua)) tren~".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sach)) vu nang xa hoi. hieu va cao luc va danh ((di ca) OR (di cua)) tren*.