Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
hieu van » hieu va, thien van, lieu va
hanh di » hanh vi, hanh de, hang di
hieu ve » hieu va
cua tre » cua te, cuu tre, cua triet
tang ma » mang may, tang van
ma hoi » mai hoi, xa hoi, ma hoa
sac ky » cac ky, sai ky
di cua » dai cua, doi cua, de cua

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 y) or (sac ky)) tang ma hoi. ((hieu ve) OR (hieu van)) am thuc van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach y) OR (sac ky)) tang ma hoi. ((hieu ve) OR (hieu van)) am thuc van hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach y) or (sac ky)) tang ma hoi. ((hieu ve) OR (hieu van)) am thuc van hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach y) or (sac ky)) tang ma hoi. ((hieu ve) OR (hieu van)) am thuc van hanh di cua tre*.