Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
hieu van » hieu va, thien van, lieu va
tu sach » su sach, te sach, tu cach
mai hoi » mai khoi, dai hoi, lai hoi
van cac » van hac, van cau, van bac
cac dat » cac dan, cai dat, cac dai
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
di cua » dai cua, doi cua, de cua

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) or (tu sach)) ky nang ((mai hoi) or (ma hoa)). hieu van cac dat va hanh di cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (tu sach)) ky nang ((mai hoi) OR (ma hoa)). hieu van cac dat va hanh di cua vat.
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (tu sach)) ky nang ((mai hoi) or (ma hoa)). hieu van cac dat va hanh di cua vat*.