1. R. Ger, Z. Kominek andM. Sablik, Generalized Smital’s Lemma and a Theorem of Steinhaus. Radovi Mat.18 (1985), 101–119.
2. E. Hewitt andK.A. Ross, Abstract Harmonic Analysis, vol.I, Springer-Verlag, Berlin-Göttingen-Heidelberg 1963.
3. Z. Kominek andM. Kuczma, Theorems of Bernstein-Doetsch, Piccard and Mehdi and Semilinear Topology. Arch. Math.52 (1989), 595–602.
4. M. Kuczma, Functional Equations in a Single Variable. PWN-Polish Scientific Publishers, Warszawa 1968.
5. M. Kuczma, Note on Microperiodic Functions. Radovi Mat.5 (1989), 127–140.