1. G.H. Hardy, E.M. Wright: An Introduction to the Theory of Numbers, 5th ed., Sect. 5.4 (Clarendon, Oxford 1984)
2. T. L. Heath: Diophantus of Alexandria (Dover, New York 1964)
3. C. F. Gauss: Disquisitiones Arithmeticae [English transl. by A. A. Clarke, Yale University Press, New Haven 1966]
4. R. Tijdeman: On the equation of Catalan. Acta Arith. 29, 197–209 (1976); “Exponential Diophantine Equations,” in Proc. Int. Congr. Math., Helsinki (1978)
5. W. Kaufmann-Bühler: Gauss. A Biographical Study (Springer, Berlin, Heidelberg, New York 1981)