Analysis of information sources in references of the Wikipedia article "Empty product" in English language version.
Hardy and Wright: 'Every positive integer, except 1, is a product of primes', Harold M. Stark: 'If n is an integer greater than 1, then either n is prime or n is a finite product of primes'. These examples — which I owe to A. J. M. van Gasteren — both reject the empty product, the last one also rejects the product with a single factor.
But also 0 is certainly finite and by defining the product of 0 factors — how else? — to be equal to 1 we can do away with the exception: 'If n is a positive integer, then n is a finite product of primes.'
