Photo Credits
| [Cover] | Thorne Films |
| Page facing inside front cover | The “Horsehead” Nebula in Orion, Hale Observatories. |
| Author’s Photo | Jay K. Klein |
| Contents pages | Lick Observatory |
| [68] | Dr. Erwin W. Mueller, The Pennsylvania State University |
| [70] | Yerkes Observatory |
| [86] | From Discovery of the Elements, Mary E. Weeks, Chemical Education Publishing Company, 1968. |
| [89] | The Central Press Photos, Ltd., and Sir John Cockcroft |
| [91] | Ernest Orlando Lawrence Livermore Laboratory |
| [93] | Samuel A. Goudsmit |
| [96] & [97] | Nobel Institute |
| [99] | Copyright © 1965 by Barbara Lovett Cline, reprinted from her volume The Questioners: Physicists and the Quantum Theory by permission of Thomas Y. Crowell, Inc., New York. |
| [105] & [106] | Nobel Institute |
| [107] | Alan W. Richards |
★ U.S. GOVERNMENT PRINTING OFFICE: 1975——640—285/14