Product reading
The agile manifesto: https://agilemanifesto.org/ and the twelve principles https://agilemanifesto.org/principles.html
The Scrum Guide and scrum.org‘s learning paths for Scrum Master and Product Owner.
Marty Cagan: Inspired, second edition. Chapter 6, “The root causes of failed product efforts” lists 10 scenarios, most of which in my opinion would be recognisable to any manager of digital projects. They are problems inherent in a project environment that a more Product approach could potentially solve. A book to read cover to cover, twice, then keep for reference.
Jeff Patton: User story mapping. If you are going to use User Stories rather than requirements documents, you may as well do it properly and User Story Mapping, especially when the stakeholders and development team are involved is a shortcut to a shared understanding and building the right thing.
Cole Mercer & Evan Kimbrell, Udemy: Become a Product Manager. A pretty comprehensive introduction, engaging and well maintained.
https://www.udemy.com/share/101rJeBUscc1tXQXg=/
The Product School, The Product Book: Free download in return for your email address. https://productschool.com/the-product-book/
Mike Cohn’s Mountain Goat Software site and blog
Roman Pichlar has published a core set of tools and blog
BOOST – A company using Agile, Product mindset and Scrum, and sharing a neat set of resources and blog articles, especially their Product Owner guide
Product Tank meet-up group. Lots of presentations by product managers. Great for tuning into and maintaining the mindset. They blog at https://www.mindtheproduct.com/