Uber Data Breach: Extra information available in the Federal Trade Commission report
The CodeCov Data breach: Blog post and Video

The scale of leaked secrets

How bad can it git : Article from NC State University
The state of secret sprawl on GitHub : Study from GitGuardian State of the octoverse : State of GitHub activity in 2020
Docker: Hunting for secrets in Docker Hub: what we’ve found

Understanding how to detect secrets

Secret sprawl and the attack surface: Episode 1 - secrets in source code
Why secrets in git are such a problem:Episode 2 - secrets in source code
Building reliable secrets detection:Episode 3 -  secrets in source code
Implementing MongoDB detector: Article from GitGuardian
Building reliable secrets detection: GitGuardian case study

Best practices manipulating secrets

GitGuardian cheatsheet : Guide to managing API keys and other credentials
Secret Detection Learning Centre: Comprehensive FAQ style guide to detecting secrets
Implementing secret detection white paper
GitHub .gitignore template files: Example .gitignore files to use
GitGuardian Shield:  open source CLI tool for pre-commit detection