This book, assembled by Henry Dreyfuss and team for original publishing in 1972, is a really great design resource. It’s a fairly exhaustive collection of different visual symbols used in all sorts of industries. Think of it as a sort of Noun Project but in book form.
As well as being a reference for everything from nautical flags to hobo symbols, it also recounts how some symbols have changed over the years, such as this excellent grid of evolving Olympic symbols:
The back of the book contains a wonderful index of symbols from all sources organized by rough shape:
But perhaps my favourite part of the edition I bought is the exuberant introduction by one Buckminster Fuller, which he concludes with:
Henry Dreyfuss’ contribution to a new world technique of communication will catalyze a world preoccupation with its progressive evolution into a worldian language so powerfully generalizes as to swiftly throw into obsolescence the almost fatally lethal trends of humanity’s age-long entrapment in specializations and the limitations that specialization imposes upon human thinking. Thus humans can be liberated to use their own cosmically powerful faculties to communicate what needs to be done in local Universe, as humans are uniquely capable of doing – and uniquely advantaged to do – by the phenomenon love and the truthfully thinking mind.