What is the source of these websites that give isoallin as the reason for the blue in garlic?

When I google isoallin I get a few sites that give the answer to “garlic…why the blue?” questions. But they don’t give sources other than what they read in other similar sites. Wikipedia is not among the google results. It gives http://en.wikipedia.org/w/index.php?title=Special%3ASearch&search=isoallin+%2Bsulphur+compound+%2B+garlic result. The 2 or 3 random chemical dictinaries also don’t recognize it. What do you think that means? Where did they get their source from? http://www.fluther.com/126722/calling-all-chemists-what-the-hell-happened-details/ is the reason for the search