Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, va hanh
va triet » va thiet, va trien, ve triet
bo sach » co sach, hoc sach
mai hoi » mai khoi, dai hoi, lai hoi
va cham » va chat
va tham » van tham, va thanh, va thuat
y nang » ky nang, ly nang, v nang
vi va » vi van, vai va, vu va

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: bo sach y nang ((mai hoi) OR (ma hoa)). hieu ((va cham) OR (va tham)) thuc vat hanh vi va triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "bo sach y nang ((mai hoi) or (ma hoa)). hieu ((va cham) OR (va tham)) thuc vat hanh vi va triet~".
• Adding a wildcard symbol may retrieve word variants: bo sach y nang ((mai hoi) or (ma hoa)). hieu ((va cham) OR (va tham)) thuc vat hanh vi va triet*.