Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thu sach » tu sach, thuat sach, thu hoach
hieu van » hieu va, thien van, lieu va
van cac » van hac, van cau, van bac
cac dai » cac dan, cac bai, can dai
va hanh » van hanh, va thanh, va danh
ma hoi » mai hoi, xa hoi, me hoi
dai va » mai va
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: ((thu sach) or (thuoc sach)) ky nang ((ma hoi) or (ma hoa)). hieu van cac dai va hanh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuoc sach)) ky nang ((ma hoi) OR (ma hoa)). hieu van cac dai va hanh vi cua vat.
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thuoc sach)) ky nang ((ma hoi) or (ma hoa)). hieu van cac dai va hanh vi cua vat*.