References

John D. Anderson, Philip A. Laing, Eunice L. Lau, Anthony S. Lui, Michael Martin Nieti, Slava G. Turyshev. Study of the anomalous acceleration of Pioneer 10 and 11.
http://arxiv.org/abs/gr-qc/0104064 (11 April 2002)

Slava G. Turyshev, Viktor T. Toth, Larry R. Kellog, Eunice L. Lau, Kyong J. Lee. The Study of the Pioneer Anomaly: New Data and Objectives for New Investigation.
http://arxiv.org/abs/gr-qc/0512121 (6 March 2006)

Viktor T. Toth and Slava G. Turyshev. The Pioneer Anomaly: seeking an explanation in newly recovered data. http://arxiv.org/abs/gr-qc/0603016 (7 March 2006)

Pound, R. V.; Rebka Jr. G. A. (November 1, 1959). Gravitational Red-Shift in Nuclear Resonance. Physical Review Letters 3 (9): 439-441. DOI:10.1103/PhysRevLett.3.439

Pound, R. V.; Snider J. L. (November 2, 1964). Effect of Gravity on Nuclear Resonance. Physical Review Letters 13 (18): 539-540. DOI:10.1103/PhysRevLett.13.539

http://www.wikipedia.org/

http://www.nasa.gov/