Canon Knowledge Base - Canonet QL17 : How to set long (bulb) exposures.
Canon R6 Bulb Mode Tutorial - YouTube
How to Use Bulb Mode for Long Exposures
Canon 5D Mark IV firmware version 1.0.4 corrects bulb mode issue - Camera Jabber
Shooting in BULB Mode with the Canon EOS M50 & Powershot G7X II | A demonstration of how to shoot in BULB mode with the Canon EOS M50 and the Powershot G7X