Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
van hanh » van thanh, ban hanh, van anh
phan duc » pham duc, phan tu, phan dau
duc van » duc va, duc tan, duc manh
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, te sach
hieu ve » hieu van
ly hang » ly quang
ty hang » ty xang, thi hang, thu hang
vi su » va su, ve su, ki 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 ((ty hang) or (ly hang)) xa hoi. ((hieu ve) OR (hieu va)) phan duc van hanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty hang) OR (ly hang)) xa hoi. ((hieu ve) OR (hieu va)) phan duc van hanh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty hang) or (ly hang)) xa hoi. ((hieu ve) OR (hieu va)) phan duc van hanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty hang) or (ly hang)) xa hoi. ((hieu ve) OR (hieu va)) phan duc van hanh vi su triet*.