[In The Electromagnetic Spectrum] Branley brings his trademark of good scientific writing, clear, accurate and concise, to bear on a difficult albeit interesting subject: the spectrum of invisible radiation that abounds throughout the universe from radio waves, light waves, infrared and ultraviolet radiation to x-rays and gamma rays…. Hard-to-grasp concepts, such as the invisibility and speed of light, are defined in context. Equations and formulas are frequent and require effort to understand as well as some mathematical background. But Branley has succeeded in presenting a complex topic with clarity, while stimulating curiosity and encouraging experimentation and study. Little on the subject for any age group exists, and what is available is primarily found in scattered chapters of physics books.
Connie Tyrrell, "Junior High Up: 'The Electromagnetic Spectrum'," in School Library Journal (reprinted from the November, 1979 issue of School Library Journal, published by R. R. Bowker Co./ A Xerox Corporation; copyright © 1979), Vol. 26, No. 3, November, 1979, p. 84.