Electronic and Experimental Music (5/e), by Thom Holmes. Routledge, 2015. ISBN 113879273X.
Holmes gives a full tour of electrical and electronic instruments, from the Teleharmonium and Theremin, tape recorders (for musique concrete), analog synthesizers, and digital and computer synthesizers.
He also looks at musicians and the music, including Schaefer, Varèse, John Cage, Stockhausen, Babbitt, Carlos, Brian Eno, Yoko Ono, and many more.
The book is well organized, with many summaries and highlights sprinkled throughout. Each major topic has recommended listening (much of which is available on YouTube). For both comprehensiveness and clarity, this is the best book I’ve found giving a tour of the field of electronic music.