Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
duc manh » suc manh, duc anh, duc minh
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
hieu va » hieu qua
duc van » duc va, duc tan, duc phan
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang

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