Introductory video's

Below is a link to the videos that briefly go over how to officiate each of the 4 strokes, individual medley, and relays. This video is a good quick refresh and a great FYI for anyone interested in the officiating process. 

https://www.youtube.com/watch?v=bPFJCbQkZnc

Stroke Briefing

https://websitedevsa.blob.core.windows.net/sitefinity/docs/default-source/officialsdocuments/officials-training-resources/clinic-resources/officials-briefing.pdf

Documents

https://www.usaswimming.org/officials/popular-resources/officials-documents