Clearman, Brian2011-08-282011-08-282010-08-08978-0-918941-33-6https://hdl.handle.net/1794/11523254 pages3rd edition of this work. The study includes an introduction, historical surveys, a classification of the spectrum of aids as well as surveys of messages, meanings, subdivisions.en-USTransportation markingsSemioticsSafety aidsBook