Tucker & Tucker 1986, p. 61-64. Tucker, Karen; Tucker, Wallace (1986). The Cosmic Inquirers: Modern Telescopes and Their Makers. Cambridge, MA: Harvard University Press. ISBN0-674-17436-4. OCLC12582170.
Tucker & Tucker 1986, p. 72-75. Tucker, Karen; Tucker, Wallace (1986). The Cosmic Inquirers: Modern Telescopes and Their Makers. Cambridge, MA: Harvard University Press. ISBN0-674-17436-4. OCLC12582170.
Tucker & Tucker 1986, p. 83. Tucker, Karen; Tucker, Wallace (1986). The Cosmic Inquirers: Modern Telescopes and Their Makers. Cambridge, MA: Harvard University Press. ISBN0-674-17436-4. OCLC12582170.
Tucker & Tucker 1986, p. 90. Tucker, Karen; Tucker, Wallace (1986). The Cosmic Inquirers: Modern Telescopes and Their Makers. Cambridge, MA: Harvard University Press. ISBN0-674-17436-4. OCLC12582170.
Tucker & Tucker 1986, p. 93-95. Tucker, Karen; Tucker, Wallace (1986). The Cosmic Inquirers: Modern Telescopes and Their Makers. Cambridge, MA: Harvard University Press. ISBN0-674-17436-4. OCLC12582170.