I would have to look it up to be honest... Is it really critical that you know? I will tell you the stupid things we do, when we formulate we find all of these cool papers (Seth and I) and we get all keen on them, make the formulations and never really save or categorize the papers. So, much of our initial data is somewhere on a computer in a file or printed in a pile. When someone asks "how do you know X is..." we can't for the life of us find the papers right when we need them.