Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hanh tai » thanh tai, hang tai, han tai
hanh dai » hanh dao, vanh dai, thanh dat
cac cac » cac cach, ca cac, cac bac
cac ban » cac dan, cac van, can ban
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
ky sang » ky nang, ky dang, ky tang
ma hoi » mai hoi, xa hoi, me hoi
ve cac » va cac, vien cac

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky sang ((ma hoi) OR (ma hoa)). hieu ve cac cac ban ((hanh dai) or (hanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky sang ((ma hoi) OR (ma hoa)). hieu ve cac cac ban ((hanh dai) OR (hanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky sang ((ma hoi) OR (ma hoa)). hieu ve cac cac ban ((hanh dai) or (hanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky sang ((ma hoi) OR (ma hoa)). hieu ve cac cac ban ((hanh dai) or (hanh tai)) cua tre*.