Convergence of Infinite Products – definition

I am working on infinite products. I found the following definition for convergence of infinite products in Wikipidea.

The product of positive real numbers $\prod_{n=1}^\infty a_n$ converges to a non zero real number if and only if the sum $\sum_{n=1}^\infty \ln(a_n)$ converges.

However, I am looking for any standard references, such as books or journals, to cite the definition. Could you name few books or journals which define the convergence of infinite products?

• What you've cited, I would call a theorem, not a definition. – Gerry Myerson Feb 23 '17 at 5:06