If you cannot locate a PDF, do not despair. The core teachings of Caesari are not unique; they are a clear crystallization of universal principles. You can reconstruct his curriculum using other texts:
Rather than focusing on forceful "support," he emphasizes a natural respiratory control that reacts to the vocal needs of the pitch and vowel. Notable Features
In The Voice of the Mind , he explains that proper phonation requires the vocal cords to close efficiently to resist the air pressure. If they are too loose, the voice is breathy; if they are slammed shut with force, the voice is harsh. He advocated for a "tidy" approximation of the cords to create a focused, ringing tone.
Edgar F. Herbert and Caesari are not widely known authors, and information about their background is scarce. However, based on the book's content, it appears that they were influenced by various spiritual and philosophical traditions.