https://cloud.spring.io/spring-cloud-sleuth/
https://cloud.spring.io/spring-cloud-sleuth/spring-cloud-sleuth.html

https://docs.spring.io/spring-cloud-sleuth/docs/current/reference/html/index.html

presentations
2018
Observability with Spring-Based Distributed Systems
    https://www.youtube.com/watch?v=PM0mO4IxpSE
How Sleuth Bravely Cracked the Case of "Too Much to Code"
    https://www.infoq.com/presentations/spring-sleuth-brave
    https://www.youtube.com/watch?v=6o9zPMiM6F0
https://www.infoq.com/presentations/distributed-tracing-spring-cloud-zipkin

whatsnew
https://spring.io/blog/2021/12/07/spring-cloud-sleuth-3-1-0-is-out