Perhaps you should try some spelling variations:
nganh khong » nganh cong, nhanh chong, nganh nong
cac nganh » hoc nganh
sach doan » sach dao, hach toan, sach danh
khong khi » khong he
so sach » so sanh, bo sach, co sach
va khi » va chi, va kha
va ki » va ky, ve ki, va vi

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 doan ((va khi) OR (va ki)) đong luc ) OR ( tu cac nganh khong khi đong luc ))~.
• Adding a wildcard symbol may retrieve word variants: (( so sach doan ((va khi) or (va ki)) đong luc ) or ( tu cac nganh khong khi đong luc ))*.