If you are into industrial and globalized signage / semiotics, do yourself a favor and check out the Symbol Sourcebook -- https://www.amazon.com/Symbol-Sourcebook-Authoritative-Inter...

Some of the symbolism they use for computer operations are fascinating

I have by my desk Henry Dreyfuss's Symbol Sourcebook [1972 edition]. It contains symbols he collected over a lifetime - he died in '72. Rococo is the fad [Perlis says it comes before rubble]. Flat design dominates when clear communication becomes more important than signalling via fashion. There's a reason stop signs don't have gradient fills.

http://www.amazon.com/Symbol-Sourcebook-Authoritative-Intern...

http://en.wikipedia.org/wiki/Henry_Dreyfuss