Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
hanh lai » hanh lam, hanh tai, thanh lap
su sach » so sach, vu sach
lai cua » dai cua, hai cua, lai chau
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky nang, ky dang, ky tang
xuc va » duc va, tuc va, luc va
ve cac » va cac

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