Perhaps you should try some spelling variations:
cham duc » pham duc, cham soc, pham duy
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach tu » sach thu, cach tu, sach ty
cong so » cong san, cong hoa
hieu va » hieu qua
va hanh » van hanh, va thanh, va danh
hanh te » hanh tu, hanh ve, hanh de
cong o » cong co, cong bo, cong ho
te su » ve su, te du, de su

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 va) OR (lieu va)) cham duc va hanh te su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu ((cong o) OR (cong so)) hoi. ((hieu va) OR (lieu va)) cham duc va hanh te su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach tu ((cong o) or (cong so)) hoi. ((hieu va) OR (lieu va)) cham duc va hanh te su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach tu ((cong o) or (cong so)) hoi. ((hieu va) OR (lieu va)) cham duc va hanh te su triet*.