Below are my recommended public resources for Product owners or anyone who is interested at Scrum:
Let's get the fundamentals right with
Agile manifesto - http://www.agilemanifesto.org/
Scrum guide - http://www.scrumguides.org/scrum-guide.html
Let's go deep into Product owner role with Certified Scrum Product Owner Training notes from Scrum Inc - http://www.scruminc.com/wp-content/uploads/2014/07/CSPO-v6-.pdf
Happy reading.