Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
pham duy » pham duc
cham duc » pham duc, cham soc, phan duc
cong so » cong san, cong hoa
sach tu » sach thu, cach tu, sach ty
va hanh » van hanh, va thanh, va danh
hanh te » hanh tu, hanh ve, hanh de
tu sach » thu sach, su sach, te sach
cong o » cong co, cong bo, cong ho
te cua » tue cua, le 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: tu sach tu ((cong o) OR (cong so)) hoi. hieu qua ((cham duc) or (pham duy)) va hanh te cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu ((cong o) OR (cong so)) hoi. hieu qua ((cham duc) OR (pham duy)) va hanh te cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach tu ((cong o) OR (cong so)) hoi. hieu qua ((cham duc) or (pham duy)) va hanh te cua triet".
• Adding a wildcard symbol may retrieve word variants: tu sach tu ((cong o) OR (cong so)) hoi. hieu qua ((cham duc) or (pham duy)) va hanh te cua triet*.