Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
vat hanh » vat thanh, van hanh, va hanh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
qua cam » qua cham, qua cac, qua ca
van cau » van dau, van hau, van chat
va cau » va cac, va dau, va cao
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

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 ky nang ((x hoi) or (o hoi)). hieu qua cam thuc vat hanh ((va cau) OR (van cau)) treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((x hoi) OR (o hoi)). hieu qua cam thuc vat hanh ((va cau) OR (van cau)) treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((x hoi) or (o hoi)). hieu qua cam thuc vat hanh ((va cau) OR (van cau)) treo".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((x hoi) or (o hoi)). hieu qua cam thuc vat hanh ((va cau) OR (van cau)) treo*.