Perhaps you should try some spelling variations:
tinh vai » tinh va, tinh hai, tinh bai
su sach » so sach, vu sach
va tinh » may tinh
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
sach ky » sac ky, sach y, sach ty
hieu vo » hieu voi, hieu va, hieu ve
xay hoi » tay hoi, cay phoi, gay thoi
luc va » duc va, tuc va, loc va
co luc » coc luc, co luy

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 ((xay hoi) OR (xa hoi)). hieu vo co luc va tinh vai ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((xay hoi) OR (xa hoi)). hieu vo co luc va tinh vai ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((xay hoi) OR (xa hoi)). hieu vo co luc va tinh vai ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((xay hoi) OR (xa hoi)). hieu vo co luc va tinh vai ((cua tre) or (cuu tre))*.