Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh dai » hanh tai, hanh dao, vanh dai
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
va cau » van cau, va cac, va dau
luc va » tuc va, loc va
cua tu » cua tuc, cua su, cua cu

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: ((tu sach) OR (toc sach)) ky nang xa hoi. hieu va cau ((luc va) OR (duc va)) hanh dai cua tu~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (toc sach)) ky nang xa hoi. hieu va cau ((luc va) OR (duc va)) hanh dai cua tu~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (toc sach)) ky nang xa hoi. hieu va cau ((luc va) OR (duc va)) hanh dai cua tu*.