Mean square limit for lattice points in a sphere Pavel M. Bleher, Freeman J. Dyson (1994) Acta Arithmetica
Mean square value of exponential sums related to representation of integers as sum of two squares Pavel M. Bleher, Freeman J. Dyson (1994) Acta Arithmetica
Mittlere Darstellungen natürlicher Zahlen als Summe von n k -ten Potenzen Ekkehard Krätzel (1973) Czechoslovak Mathematical Journal