Thanks Harris!
But I have one more question.Do I need to see the text in 3dimensional like the stereograms? Because now I can remember that I used to play with it (3dimensional text and checked math copybook like the tiled floor),and now I'm practicing with the stereograms,but I can't make the same with the text,altough I remember,that I used to make 5-6 years before (it's a bit annoying)
