1. Andres J., Fišer J., Metric and topological multivalued fractals, Int. J. Bifurc. Chaos Appl. Sci. Engn., 2004, 14, 1277–1289
2. Andres J., Fišer J., Gabor G., Leśniak K., Multivalued fractals, Chaos Solitons & Fractals, 2005, 24, 665–700
3. Bakhtin I.A., The contraction mapping principle in almost metric spaces, Funct. Anal, Gos. Ped. Inst. Unianowsk, 1989, 30, 26–37
4. Barnsley M.F, Fractals Everywhere, Academic Press, Boston, 1988
5. Berinde V, Generalized contractions in quasimetric spaces, Seminar on Fixed Point Theory, 1993, 3–9