Perhaps you should try some spelling variations:
hieu quan » hieu qua, lieu quan, thien quan
ve triet » va trien, su triet
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
cau hoc » cau hoi, cau hoa, cao hoc
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
cau loc » hau loc, cau luc, cau long
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
vi ve » va ve, gi ve, ve ve

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky lang xa hoi. hieu quan ((cau loc) OR (cau hoc)) ((van hanh) OR (ban hanh)) vi ve triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky lang xa hoi. hieu quan ((cau loc) or (cau hoc)) ((van hanh) OR (ban hanh)) vi ve triet~".
• Adding a wildcard symbol may retrieve word variants: so sach ky lang xa hoi. hieu quan ((cau loc) or (cau hoc)) ((van hanh) OR (ban hanh)) vi ve triet*.