[1] Christiansen S.: Polynomial with Complex Argument. (in Danish). Regnecentralen, Copenhagen (1962).

[2] Christiansen S., J. Bach Andersen: Parametric Curves for Radiation from a Vertical Dipole near a Coastline. Report R 29, Laboratory of Electromagnetic Theory, Technical University, Copenhagen (1963).

[3] Christiansen S.: Complex Squareroot. (in Danish). Regnecentralen, Copenhagen (1963).

[4] Christiansen S.: Error Integral with Complex Argument. ALGOL Procedure. BIT, Nordisk Tidskr. Informations-Behandling 5, 287-293 (1965).

[5] Christiansen S.: Some Numerical Investigations in Connection with Application of the Compensation Theorem to Mixed Path Propagation Problems. Report R 41, Laboratory of Electromagnetic Theory, The Technical University of Denmark, Lyngby (1965).

[6] Faddeyeva V. N., N. M. Terenťev: Tables of Values of the Function $w(z) = \exp^{-z^2} \left( 1+ \frac{2i}{\sqrt{\pi}} \int_0^z \exp{t^2} dt \right) $ for Complex Argument. Oxford: Pergamon Press. 1961. MR 0122013

[7] Horner F.: A Table of a Function used in Radio Propagation Theory. Proc. Institution Elec. Engrs., Part C 102, 134-137 (1955). MR 0070248

[8] Kaplan S.: On Finding the Square Root of a Complex Number. Math. Tables Aids Comput. 4, 177-178 (1950).

[9] Lanczos C.: Applied Analysis. London: Sir Isaac Pitman & Sons. 1957.

[10] Naur P. (ed.): A Manual of GIER ALGOL 4. Copenhagen: Regnecentralen.

[11] Norton K. A.: The Propagation of Radio Waves Over the Surface of the Earth and in the Upper Atmosphere. Part I: Ground- Wave Propagation from Short Antennas. Proc. Institute Radio Engrs. 24, 1367- 1387 (1936).