Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nam xuc » cam xuc, nam xua, nam thuc
va tinh » may tinh
tinh vi » trinh vi, tinh voi, tinh va
cua tre » cua te, cuu tre, cua triet
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 nang ((o hoi) or (xa hoi)). hieu van nam xuc va tinh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((o hoi) OR (xa hoi)). hieu van nam xuc va tinh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((o hoi) or (xa hoi)). hieu van nam xuc va tinh vi cua tre*.