The Social Justice Advocate's Handbook: A Guide to Gender
This book offers clear, easily-digested, and practical explanations of one of the most commonly misunderstood things about people. Auther Sam Killermann dissects gender using a comprehensive, non-binary toolkit, with a focus on making this subject accessible and enjoyable. All this to help you understand something that is so commonly misunderstood, but something we all think we get: gender.
This book helps individuals better understand gender themselves (their gender and others'), and is a great resource for people who are doing gender education work with others.
The book is available as PDF or in print via http://www.guidetogender.com/.
Sam Killermann's website also offers a range of resources.