Perhaps you should try some spelling variations:
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
cau luc » cau truc, cau phuc
sach ty » sach y, sach tu, sach thu
so viet » hoc viet
hieu ve » hieu va, hieu van
luc va » duc va, tuc va, loc va
ma hoi » mai hoi, xa hoi, me hoi
ve cau » ke cau, va cau, ve cac

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 ty xang ((ma hoi) or (ma hoa)). hieu ve cau luc va hanh vi ((su viet) OR (so viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty xang ((ma hoi) OR (ma hoa)). hieu ve cau luc va hanh vi ((su viet) OR (so viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty xang ((ma hoi) or (ma hoa)). hieu ve cau luc va hanh vi ((su viet) OR (so viet))".
• Adding a wildcard symbol may retrieve word variants: su sach ty xang ((ma hoi) or (ma hoa)). hieu ve cau luc va hanh vi ((su viet) OR (so viet))*.