There is an exhibit right now at the Cooper Hewitt Design Museum in NYC about the work of Henry Dreyfuss did with his Symbol Sourcebook (https://www.cooperhewi

There is an exhibit right now at the Cooper Hewitt Design Museum in NYC about the work of Henry Dreyfuss did with his Symbol Sourcebook (https://www.cooperhewitt.org/channel/give-me-a-sign/ https://www.cooperhewitt.org/channel/give-me-a-sign/) which heavily influenced the design of most symbols we use today, including this one. You can view most of the exhibit online: https://collection.cooperhewitt.org/exhibitions/2318807647/ https://collection.cooperhewitt.org/exhibitions/2318807647/ Worth taking a look!