Perhaps you should try some spelling variations:
vai thiet » va thiet, tai thiet, van thiet
thanh va » thanh van, hanh va, thanh ha
va thanh » gia thanh, ban thanh, va tinh
cong tac » cong ty
thuc va » thuc vat, thuc dan, thuc day
ca thuc » can thuc, cay thuc, va thuc
su sach » so sach
cong ha » cong hoa, dong ha, cong san
vu sach » vu bach, vu khach
qua ca » qua cac, qua cua, qua cai
va vai » va bai, va van, va dai

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (vu sach)) tai ((cong ha) OR (cong tac)) hoi. hieu qua ca thuc va thanh va vai thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) tai ((cong ha) OR (cong tac)) hoi. hieu qua ca thuc va thanh va vai thiet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu sach)) tai ((cong ha) OR (cong tac)) hoi. hieu qua ca thuc va thanh va vai thiet*".