Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hieu va » lieu va, hieu qua
va hanh » va thanh, va danh, ban hanh
cam duc » cam xuc, cao duc, pham duc
tu sach » thu sach, su sach, te sach
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
bo sach » co sach, hoc sach
vai cua » dai cua, hai cua, lai cua
ma hoi » mai hoi, xa hoi, ma hoa
va cam » va cham, va cac, va cao

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (bo sach)) ky tang ma hoi. hieu va cam duc ((va hanh) OR (van hanh)) vai cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (bo sach)) ky tang ma hoi. hieu va cam duc ((va hanh) OR (van hanh)) vai cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (bo sach)) ky tang ma hoi. hieu va cam duc ((va hanh) OR (van hanh)) vai cua vat".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (bo sach)) ky tang ma hoi. hieu va cam duc ((va hanh) OR (van hanh)) vai cua vat*.