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

For this source they list America’s Test Kitchen Newsletter, September 2004 as the information source.

I may not understand your question. I apologize in advance if I am way off here.

@SpatzieLover thanks you are not way off. I was just wondering why these cooking websites are siting other other cooking websites as their sources instead of one of the foremost authorities in the subject. I went to What’s Cooking America, which is also listed in the source you provided, it got it from International Journal of Food Science & Technology (Wiley-Blackwell).
And why does the word not come up in Google as I type isoall… that is it. The next word is Isoalloxazine . I mean if it can provide me with sites that talk about it…And Wikipedia doesn’t have it either, so is that odd?

Wiki pages can be written and edited by anyone. Maybe you’d like to edit the page and add the source…or at least inform them the source is missing.

@SpatzieLover but I would rather leave the editing to the experts. Who are the recognized authorities on the subject? International Journal of Food Science & Technology (Wiley-Blackwell)? I don’t know.