Perhaps you should try some spelling variations:
va thanh » ban thanh, va tinh, le thanh
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
dang xa » dang xay, lang xa, dang ha
cao hoc » cho hoc, chat hoc
vi cua » vai cua, di cua
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ky dang xa hoi. hieu qua ((cao hoc) OR (co hoc)) ((va thanh) or (gia thanh)) vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky dang xa hoi. hieu qua ((cao hoc) OR (co hoc)) ((va thanh) OR (gia thanh)) vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky dang xa hoi. hieu qua ((cao hoc) OR (co hoc)) ((va thanh) or (gia thanh)) vi cua te".
• Adding a wildcard symbol may retrieve word variants: so sach ky dang xa hoi. hieu qua ((cao hoc) OR (co hoc)) ((va thanh) or (gia thanh)) vi cua te*.