Below are the names of books written by expertise like Esther Derby, Ken Schwaber, Mike Cohn, Alistair Cockburn, Kenneth S. Rubin. You can refer these books to gather more knowledge on Agile development.

Agile Software Development with Scrum (Series in Agile Software Development) – Paperback – October 21, 2001 by Ken Schwaber and Mike Beedle
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Agile Project Management with Scrum (Developer Best Practices) Paperback – February 21, 2004 by Ken Schwaber
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Agile Retrospectives: Making Good Teams Great Paperback – August 5, 2006 by Esther Derby
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Agile Estimating and Planning Paperback– November 11, 2005 by Mike Cohn
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User Stories Applied: For Agile Software Development Paperback – March 11, 2004 by Mike Cohn
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Essential Scrum: A Practical Guide to the Most Popular Agile Process (Addison-Wesley Signature Series (Cohn)) Paperback – August 5, 2012 by Kenneth S. Rubin
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Agile Software Development: The Cooperative Game – 2nd Edition By Alistair Cockburn (ISBN #0321482751)

The Software Project Manager’s Bridge to Agility By Michele Sliger, Stacia Broderick (ISBN #0321502752)

Coaching Agile Teams By Lyssa Adkins (ISBN #0321637704)

Agile Project Management: Creating Innovative Products – 2nd Edition By Jim Highsmith (ISBN #0321658396)

Becoming Agile: …in an imperfect world By Greg Smith, Ahmed Sidky (ISBN #1933988258)

Agile Estimating and Planning By MikeCohn (ISBN #0131479415)

The Art of Agile Development By James Shore (ISBN #0596527675)

User Stories Applied: For Agile Software Development By MikeCohn (ISBN #0321205685)

Agile Project Management with Scrum By Ken Schwaber (ISBN #073561993X)

Lean-Agile Software Development: Achieving Enterprise Agility By Alan Shalloway, Guy Beaver, James R. Trott (ISBN #0321532899)