Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nha tang » nha trang, nham tang, ha tang
mai hoi » mai khoi, dai hoi, lai hoi
va cham » va chat, va tham
va hanh » van hanh, va thanh, va danh
ma hoi » xa hoi, ma hoa, me hoi
va cao » va cac, va co, va dao
vi cua » vai cua, di cua

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: toc sach nha tang ((ma hoi) OR (mai hoi)). hieu ((va cham) OR (va cao)) duc va hanh vi cua vat~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach nha tang ((ma hoi) OR (mai hoi)). hieu ((va cham) or (va cao)) duc va hanh vi cua vat~".
• Adding a wildcard symbol may retrieve word variants: toc sach nha tang ((ma hoi) OR (mai hoi)). hieu ((va cham) or (va cao)) duc va hanh vi cua vat*.