Perhaps you should try some spelling variations:
hieu quan » lieu quan, thien quan, lien quan
su sach » so sach, vu sach
hang co » hang cho, hang ca, nang co
dao luc » dao duc, dao tuc, bao luc
va hanh » van hanh, va thanh, va danh
vai cua » dai cua, hai cua, lai cua
y hang » ly hang, ty hang, yu hang
luc va » duc va, tuc va, loc va
vi cua » di 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 y hang co hoc. ((hieu quan) or (hieu qua)) dao luc va hanh ((vi cua) OR (vai cua)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y hang co hoc. ((hieu quan) OR (hieu qua)) dao luc va hanh ((vi cua) OR (vai cua)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y hang co hoc. ((hieu quan) or (hieu qua)) dao luc va hanh ((vi cua) OR (vai cua)) triet".
• Adding a wildcard symbol may retrieve word variants: su sach y hang co hoc. ((hieu quan) or (hieu qua)) dao luc va hanh ((vi cua) OR (vai cua)) triet*.