Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
may hoi » may thoi, tay hoi, mai hoi
hieu va » lieu va, hieu qua
xuc van » luc van, vuc van, xuc ban
duc van » duc va, duc tan, duc manh
y mang » cay mang
va cau » van cau, va cac, va cao
vi dau » vi dai, bi dau, ve dau
va dau » va dao

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 y mang may hoi. hieu va cau ((xuc van) OR (duc van)) thanh ((vi dau) or (va dau)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y mang may hoi. hieu va cau ((xuc van) OR (duc van)) thanh ((vi dau) OR (va dau)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y mang may hoi. hieu va cau ((xuc van) OR (duc van)) thanh ((vi dau) or (va dau)) tren".
• Adding a wildcard symbol may retrieve word variants: thu sach y mang may hoi. hieu va cau ((xuc van) OR (duc van)) thanh ((vi dau) or (va dau)) tren*.