Published in 1973, this book on modern musical notation explores avant garde musical notation of the time. From the preface:
...an increasing number of choral composers are more or less inventing their own musical language and the means of notating it. This new notation is usually defined, often in great detail, in a preface to each composition. We have examined a body of this material and extraced the notational symbols which appear with greatest frequency. This is a time capsule of modern choral composition of the 1970's and offers notations for unusual musical expressions that can still be used today.