Perhaps you should try some spelling variations:
thanh van » thanh san, thanh toan, thanh phan
ban thanh » ban hanh, ban hang
su sach » so sach, vu sach
cao duc » dao duc, cao suc, tao duoc
van cua » vang cua, ban cua, dan cua
sach ty » sach y, sach tu, sach thu
hieu va » lieu va
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty nang xa hoi. ((hieu va) OR (hieu qua)) ((cao duc) or (giao duc)) ban thanh van cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang xa hoi. ((hieu va) OR (hieu qua)) ((cao duc) OR (giao duc)) ban thanh van cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty nang xa hoi. ((hieu va) OR (hieu qua)) ((cao duc) or (giao duc)) ban thanh van cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty nang xa hoi. ((hieu va) OR (hieu qua)) ((cao duc) or (giao duc)) ban thanh van cua tre*.