Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
va thanh » gia thanh, ban thanh, le thanh
sach ky » sac ky, sach y, sach ty
va tinh » may tinh
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
hieu ve » hieu van
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
cac lop » cac hop, cac loai
vi cua » vai cua, di cua

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: su sach ky lang xa hoi. ((hieu ve) OR (hieu va)) cac lop ((va thanh) OR (va tinh)) vi cua viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky lang xa hoi. ((hieu ve) or (hieu va)) cac lop ((va thanh) OR (va tinh)) vi cua viet~".
• Adding a wildcard symbol may retrieve word variants: su sach ky lang xa hoi. ((hieu ve) or (hieu va)) cac lop ((va thanh) OR (va tinh)) vi cua viet*.