[math-fun] a certain formula of Euler, primes and Pi

Hello, I have a friend in Moncton (NB, canada) a math professor, Paul Deguire, browsing around with the history of math and came accros this formula (well known ?) of pi : http://en.wikipedia.org/wiki/List_of_formulae_involving_%CF%80 see the center of the page with prime numbers, also this one http://mathworld.wolfram.com/PiFormulas.html formulas 60 and 61. It deals with prime numbers , an infinite product and pi. Is there someone that knows a reference for this formula, when it was found by Euler ? Any information that would enlight this almost pi day, Best regards, Simon Plouffe