Ramanujan-Petersson conjecture

expositions

• http://www.math.ucla.edu/~jonr/eprints/lub.pdf
• Blomer, Valentin, and Farrell Brumley. 2013. “The Role of the Ramanujan Conjecture in Analytic Number Theory.” Bulletin of the American Mathematical Society 50 (2): 267–320. doi:10.1090/S0273-0979-2013-01404-6.
• http://www.claymath.org/publications/Harmonic_Analysis/chapter9.pdf

questions

• http://mathoverflow.net/questions/19169/reference-request-for-a-proof-of-ramanujans-tau-conjecture