We study the properties of complex-valued functions of a complex variable, whose real and imaginary parts satisfy a second-order skew-symmetric strongly elliptic system with constant real coefficients in the plane. The behavior of such functions and their dilatations near singular points is investigated and the dependence of the type of the singularity on the form of the Laurent expansion of the function under consideration is established. The principle of the argument is established for the functions with poles under study, analogs of the Ruschet and Hurwitz theorems are proved