Wi-Fi Alliance: The main industry body for promoting Wi-Fi and certifying interoperability.
IEEE 802 and IEEE 802.11: Standards groups for local area networks and Wi-Fi.
Li-Fi Consortium: Li-Fi is a fast, inexpensive optical wireless communication system that may be useful as an alternative to Wi-Fi in some environments and for some requirements.
Wi-Fi 6 (IEEE 802.11ax) was standardized since book publication:
WLAN 802.11ax Tutorial-Basic features, frame, modes, PHY, MAC: Tutorial on Wi-Fi 6 with many tutorial and historical links plus a more general Wireless LAN Tutorial.
Deep Dive Into Wi-Fi 6: Detailed webinar by Cisco.
Here is information on Wi-Fi 7 (IEEE 802.11be)
What Is Wi-Fi 7? by Intel
Bluetooth SIG: Contains all the standards, numerous other documents, and news and information on Bluetooth companies and products.
IEEE 802.15 Working Group on Personal Area Networks: Covers Bluetooth and related networks.
Connectivity Standards Alliance: The Zigbee Alliance is now the Connectivity Standards Alliance. Site provides white papers, documents, and vendor information.
3GPP: A consortium of wireless companies that standardize and promote 4G/5G. All of the standards are provided at this site.
Cellular Telecommunications and Internet Association: Another industry consortium.
Next Generation Mobile Networks (NGMN) Alliance: Useful collection of technical documents, including the two influential White Papers.
5G Americas: A trade group of Western Hemisphere companies supporting TDMA, GSM, GPRS, EDGE, and UMTS. Includes industry news, white papers, and other technical information.
5G technology was standardized since book publication:
5G Wireless: A Comprehensive Introduction: A new textbook by co-author William Stallings
3GPP Release 15 Overview: Published in IEEE Spectrum
The ABCs of 5G New Radio Standard Ebook: by Keysight Technologies, a prominent 5G network emulation provider.
Everything you need to know about 5G: By Qualcomm