Perhaps you should try some spelling variations:
ban hang » ngan hang
cac duc » cac du, cao duc, cac dac
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
sach ky » sach y, sach ty, sach kem
hieu ve » hieu va, hieu van
nang ma » tang ma, sang ma, nang cao
sac ky » cac ky, sai ky
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: te ((sach ky) or (sac ky)) nang ma hoa. hieu ve cac duc ((ban hanh) or (ban hang)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sac ky)) nang ma hoa. hieu ve cac duc ((ban hanh) OR (ban hang)) vai cua tre.
• Adding a wildcard symbol may retrieve word variants: te ((sach ky) or (sac ky)) nang ma hoa. hieu ve cac duc ((ban hanh) or (ban hang)) vai cua tre*.