Perhaps you should try some spelling variations:
mai khoi » mai khoa, tai khoa, cac khoi
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
van cac » van hac, van cau, van bac
cac dat » cac dan, cai dat, cac dai
va hanh » van hanh, va thanh, va danh
ma hoi » mai hoi, xa hoi, ma hoa
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang ((ma hoi) or (mai khoi)). hieu van cac dat va hanh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((ma hoi) OR (mai khoi)). hieu van cac dat va hanh vi cua vat.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((ma hoi) or (mai khoi)). hieu van cac dat va hanh vi cua vat*.