Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
hanh hai » thanh hai, nhanh hai, hang hai
su sach » so sach, vu sach
hai cua » thai cua, dai cua, hoi cua
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
ve cac » va cac
y sang » _ sang, duy sang
xuc va » duc va, tuc va, luc va
ma hoi » mai hoi, ma hoa, me hoi

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: su sach y sang ((ma hoi) OR (xa hoi)). hieu ((ve cac) OR (vien cac)) xuc va hanh hai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y sang ((ma hoi) or (xa hoi)). hieu ((ve cac) OR (vien cac)) xuc va hanh hai cua tre~".
• Adding a wildcard symbol may retrieve word variants: su sach y sang ((ma hoi) or (xa hoi)). hieu ((ve cac) OR (vien cac)) xuc va hanh hai cua tre*.