P. Friedland, Algorithm 312: Absolute value and square root of a complex number, Communications of the ACM, vol.10, issue.10, p.665, 1967.
DOI : 10.1145/363717.363780

T. E. Hull, T. F. Fairgrieve, and P. T. Tang, Implementing complex elementary functions using exception handling, ACM Transactions on Mathematical Software, vol.20, issue.2, pp.215-244, 1994.
DOI : 10.1145/178365.178404

URL : http://www.cs.toronto.edu/pub/reports/na/cmplx-elem-fcns.ps.Z

C. Jeannerod and S. M. Rump, On relative errors of floating-point operations: optimal bounds and applications, 2014. Manuscript available at https://hal.inria.fr/hal-00934443

W. Kahan, Branch cuts for complex elementary functions or much ado about nothing's sign bit, The State of the Art in Numerical Analysis, pp.165-211, 1987.

D. E. Knuth, The Art of Computer Programming Seminumerical Algorithms, 1998.