It is being reported recently (example) that the Turkish government has banned a geometry textbook because the letters $FG$, which are the initials of an alleged plotter of the 2016 coup d'etat attempt, appear as a line in a diagram.
What is the problem or diagram that was suppressed? What is the textbook?
I guess this is what you are looking for: http://turkeypurge.com/turkey-bans-math-textbooks-due-to-questions-including-gulens-initials