https://web.archive.org/web/20190311194130/http://blog.ptsecurity.com/2015/07/best-reverser-write-up-analyzing.html
Ptsecurity seems like the Positive Technologies blog (a Russian security company)
They had a contest the goal of which was to analyze an obscure file, with lack of documentation and perhaps even support in popular decompilers. The solution is described in detail but I have a hard time understanding it for now.
What's interesting, they said there's demand for firmware analysis, which the contest was aiming to test. I wonder if this holds up, even though the post is a decade old already.
https://web.archive.org/web/20260709032114/https://beginners.re/ Seems like a good book, there's even a huge list of universities that refer to it.