The current "official" reading list sucks. Hopefully Cisco will update it, but there is a lot of older books on there, certainly not suitable for the new exam.
In this post I will list a few of the more suitable books for the new exam. Some have not been released yet, and some are old, but extremely useful, so do check out the Amazon marketplace, as there are some bargains to be had!
FirePOWER
Cisco Next-Generation Security Solutions: All-in-one Cisco ASA Firepower Services, NGIPS, and AMP
Authors: Omar Santos, Panos Kampanakis, Aaron Woland
ISBN: 978-1587144462
SSFIPS Securing Cisco Networks with Sourcefire Intrusion Prevention System Study Guide: Exam 500-285
Authors: Todd Lammle Alex Tatistcheff, John Gay
ISBN: 978-1119155034
ASA
Cisco ASA: All-in-one Next-Generation Firewall, IPS, and VPN Services (3rd Edition)Authors: Jazib Frahim, Omar Santos, Andrew Ossipov
ISBN: 978-1587143076
IPv6
IPv6 SecurityAuthors: Scott Hogg, Eric Vyncke
ISBN: 061-9472055946
IOS/IOS-XR
IP Routing on Cisco IOS, IOS XE, and IOS XR: An Essential Guide to Understanding and Implementing IP Routing ProtocolsAuthors: Brad Edgeworth, Aaron Foss, Ramiro Garza Rios
ISBN: 978-1587144233
ESA
Email Security with Cisco IronPortAuthor: Chris Porter
ISBN: 061-9472142929
ISE
Practical Deployment of Cisco Identity Services Engine (ISE): Real-World Examples of AAA DeploymentsAuthors: Andy Richter, Jeremy Wood
ISBN: 978-0128044575
Cisco ISE for BYOD and Secure Unified Access
Authors: Jamey Heary, Aaron Woland
ISBN: 978-1587143250
ACS
AAA Identity Management SecurityAuthors: Vivek Santuka, Premdeep Banga, Brandon J. Carroll
ISBN: 061-9472141441
NetFlow/IPFIX
Network Security with NetFlow and IPFIX: Big Data Analytics for Information SecurityAuthor: Omar Santos
ISBN: 978-1587144387
VPNS: GETVPN, FlexVPN, DMVPN etc
The Complete Cisco VPN Configuration GuideAuthor: Richard Deal
ISBN: 978-1587052040
IKEv2 IPsec Virtual Private Networks: Understanding and Deploying IKEv2, IPsec VPNs, and FlexVPN in Cisco IOS
Authors: Graham Bartlett, Amjad Inamdar
ISBN: 978-1587144608
VPNs and NAT for Cisco Networks
Author: Stuart Fordham
ISBN: 978-1507646588
ACI, EVPN, VXLAN, NVGRE
Building Data Centers with VXLAN EVPNAuthors: Lukas Krattiger, Shyam Kapadia, David Jansen
ISBN: 978-1587144677
The Policy Driven Data Center with ACI: Architecture, Concepts, and Methodology
Authors: Lucien Avramov, Maurizio Portolani
ISBN: 978-1587144905
General
Router Security Strategies: Securing IP Network Traffic PlanesAuthors: Gregg Schudel, David Smith
ISBN: 061-9472053362
LAN Switch Security: What Hackers Know About Your Switches
Authors: Eric Vyncke, Christopher Paggen
ISBN: 061-9472052563
IoT
IoT Fundamentals: Networking Technologies, Protocols, and Use Cases for the Internet of ThingsAuthors: David Hanes, Gonzalo Salgueiro, Patrick Grossetete, Subodh Gajare
ISBN: 978-1587144561
SDN
Programming and Automating Cisco Networks: A guide to network programmability and automation in the data center, campus, and WANAuthors: Ryan Tischer, Jason Gooley
ISBN: 978-1587144653