This document describes the process to collect a good wireless sniffer trace in order to analyze and troubleshoot 802.11 behavior.
Analyze and Troubleshoot 802.11 Wireless Sniffing - Cisco
Cisco CCNA Wireless Part III
Analyze and Troubleshoot 802.11 Wireless Sniffing - Cisco
IEEE 802.3: A Wireshark Lab
Demo Video: Sniffer Mode in CUWN
Analyze and Troubleshoot 802.11 Wireless Sniffing - Cisco
Analyze and Troubleshoot 802.11 Wireless Sniffing - Cisco
Wireless Sniffing with Wireshark
Analyze and Troubleshoot 802.11 Wireless Sniffing - Cisco
Wireless Sniffer Capture (How to)