Marty Cagan is one of the most influential voices and has written a lot of stuff about product management for much more than a decade. I have a learnt a lot from reading his articles which can be found here.
He has written a really great book which is a must read for Product Managers: Inspired: How to create products customers love
In this Video delivered at #mtpcon 2016 he looks at profiles of six highly successful product managers and their products. It a good watch.