Subject: How was the Krebs cycle discovered (what did the experiment look like)?

I am a teacher and a student asked me how we know all the stuff about the 
Krebs and Calvin cycle.  I was not sure because I have never been taught that, 
so I tried to find it and could not.  Now I am curious to find out the actual 
details of the experiment.  I am very familiar with how the Krebs cycle works, 
but just wish to understand how Krebs actually determined and proved it.

Re: How was the Krebs cycle discovered (what did the experiment look like)?