Perhaps you should try some spelling variations:
thanh hoi » thanh hoai, thanh hoa, thanh hai
nhan duc » nhan duoc, phan duc, than duc
nhan luc » nang luc
hieu van » thien van, lieu va, hieu ve
va thanh » gia thanh, ban thanh, va tinh
hoi cua » hoi chuc
so sach » so sanh, bo sach, co sach
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
xang xa » lang xa, mang xa, ang xa
cua tre » cua te, cuu tre, cua triet

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: so sach ty xang xa hoi. ((hieu van) OR (hieu va)) ((nhan duc) OR (nhan luc)) va thanh hoi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty xang xa hoi. ((hieu van) or (hieu va)) ((nhan duc) OR (nhan luc)) va thanh hoi cua tre~".
• Adding a wildcard symbol may retrieve word variants: so sach ty xang xa hoi. ((hieu van) or (hieu va)) ((nhan duc) OR (nhan luc)) va thanh hoi cua tre*.