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 » nam thuc, cam thu, can thuc
tu sach » thu sach, su sach, te sach
sach ly » sach y, sach lo, sach ty
ly hang » ly quang
hanh di » hanh de, hang di, danh di
va hoi » xa hoi, va hoc, va hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ly hang va hoi. hieu van ((cam thuc) OR (am thuc)) va ((hanh di) or (hanh vi)) cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ly hang va hoi. hieu van ((cam thuc) OR (am thuc)) va ((hanh di) OR (hanh vi)) cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ly hang va hoi. hieu van ((cam thuc) OR (am thuc)) va ((hanh di) or (hanh vi)) cua triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ly hang va hoi. hieu van ((cam thuc) OR (am thuc)) va ((hanh di) or (hanh vi)) cua triet*.