Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
mai hoi » mai khoi, dai hoi, lai hoi
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
cac duc » cac du, cao duc, cac dac
qua cac » cua cac
di cau » da cau, diem cau
sac ky » cac ky
ma hoi » xa hoi, ma hoa, me hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sac ky) OR (sai ky)) nang ((ma hoi) or (mai hoi)). hieu qua cac duc va hanh di cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sac ky) OR (sai ky)) nang ((ma hoi) OR (mai hoi)). hieu qua cac duc va hanh di cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sac ky) OR (sai ky)) nang ((ma hoi) or (mai hoi)). hieu qua cac duc va hanh di cau tren".
• Adding a wildcard symbol may retrieve word variants: tu ((sac ky) OR (sai ky)) nang ((ma hoi) or (mai hoi)). hieu qua cac duc va hanh di cau tren*.