brain.jpg:
 - source: https://commons.wikimedia.org/wiki/File:Section_of_the_brain,_19th_century._Wellcome_L0000838.jpg
 - license: CC-BY-4.0

brain1.jpg
 - source: https://commons.wikimedia.org/wiki/File:Charles_Bell,_The_anatomy_of_the_brain_Wellcome_L0025507.jpg
 - license: CC-BY-4.0

firehosereel.jpg
 - Author: Copyright (C) 2022 Bernard Gray <bernard.gray@gmail.com>
 - License: CC0
 
gears.jpg
 - source: https://flic.kr/p/x8YA2b
 - Author: Mustang Joe (https://www.flickr.com/photos/mustangjoe/)
 - License: Public Domain 
 
scream.jpg
 - source: https://flic.kr/p/9deZXv
 - author: 	Albert Londe (?)
 - license: No known copyright restrictions
 
smoke.jpg
 - source: https://www.publicdomainpictures.net/en/view-image.php?image=197358&picture=smoke-25
 - author: 	RAJESH misra
 - license: CC0

speaker.jpg
 - source: https://commons.wikimedia.org/wiki/File:Tannoy_Little_Gold_monitor_-_professional_studio_loudspeaker_box.jpg
 - author: 	[Pittigrilli](https://commons.wikimedia.org/wiki/User:Pittigrilli)
 - license: CC-BY-4.0
 
speakertruck.*
 - source: https://commons.wikimedia.org/wiki/File:Horn_loudspeaker_truck_1929.jpg
 - Author: C. Sterling Gleason
 - License: Public Domain