The link to a Fine Arts Connoisseur magazine piece featuring Mann is here, and a gallery web page regarding Mann is here. They contain snippets of biographical information.
Mann's style is a combination of sketchy, impressionistic backgrounds delivered using a variety of means for attacking a wood panel with paint along with tightly-painted details, especially in his depictions of beautiful women. He is also hugely prolific, as his own web site reveals. Click on the images below to enlarge.