Perhaps you should try some spelling variations:
thanh vi » hanh vi, thanh va, thanh ve
va thanh » gia thanh, ban thanh, va tinh
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach y, sach kem
nam xuc » cam xuc, nam xua, nam thuc
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
xuc va » duc va, tuc va, luc va
vi cua » vai cua, di cua
o hoi » co hoi, o hoc, o hai

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