Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
hieu van » hieu va, thien van, lieu va
cam thuc » am thuc, nam thuc, can thuc
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
cam thu » nam thu, cac thu, ca thu
sach ty » sach y, sach tu, sach thu
lang xa » lang ha, dang xay, lang van
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 ty) or (cac ky)) lang xa hoi. hieu van ((cam thuc) OR (cam thu)) va hanh di cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (cac ky)) lang xa hoi. hieu van ((cam thuc) OR (cam thu)) va hanh di cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) or (cac ky)) lang xa hoi. hieu van ((cam thuc) OR (cam thu)) va hanh di cua triet".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (cac ky)) lang xa hoi. hieu van ((cam thuc) OR (cam thu)) va hanh di cua triet*.