A childhood memory... a woman from Friuli took care of me during the day, when I was a young child. She made the best Italian lemon cookies I have ever tasted. By complete serendipity I ran across a very similar recipe today, and have resolved to make it. The problem is that it calls for ammonium bicarbonate. I've taken the occasional look over the years, but have never seen it in Italian shops. As I recall, though being then only 4 or 5 years old at the time, the jar in which it came had a label that was a brown background with pale yellow script, and the brand might have been something like "Limonia". I don't need that specific brand (though that would be magic!), but I need to know... where to get ammonium bicarbonate?