Perhaps you should try some spelling variations:
ban hanh » ban hang
cham hoi » cham voi, cham h'roi, pham hoai
mai khoi » mai khoa, tai khoa, cac khoi
tu sach » thu sach, su sach, te sach
hieu vu » hieu va, hieu ve, hieu su
hoi ban » hoi dan, hoi bai, doi ban
ky sang » ky nang, ky dang, ky tang
mai hoi » dai hoi, lai hoi, mai doi
vu cham » va cham, vu kham, tu cham
vi cua » vai cua, di cua
cua te » cua tu
tu can » tu ban, tu cac, thu canh

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: ((tu sach) OR (tu can)) ky sang ((mai hoi) OR (mai khoi)). hieu vu cham hoi ban hanh vi cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (tu can)) ky sang ((mai hoi) OR (mai khoi)). hieu vu cham hoi ban hanh vi cua te~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (tu can)) ky sang ((mai hoi) OR (mai khoi)). hieu vu cham hoi ban hanh vi cua te*.