[1] C. Carathéodory: Über das lineare Mass von Punktmengen - eine Verallgemeinerung des Längenbegriffs. Gött. Nachr., 1914, 404-426.

[2] F. Hausdorff: Dimension und äusseres Mass. Mathematische Annalen, 79, 1919, 157-179.

[3] L. Carleson: Selected Problems on Exceptional Sets. Van Nostrand Co., 1967. MR 0225986 | Zbl 0189.10903

[4] H. Federer: Geometric Measure Theory. Springer-Verlag, 1969. MR 0257325 | Zbl 0176.00801

[5] C. A. Rogers: Hausdorff Measures. Cambridge University Press, 1970. MR 0281862 | Zbl 0204.37601

[6] R. Harvey J. Polking: Removable singularities of solutions of linear partial differential equations. Acta matematica, 125, 1970, 39-56. MR 0279461

[7] J. Král: Removable singularities of solutions of semielliptic equations. Rendiconti di Mate- matica (4) Vol. 6, Serie VI, 1973, 1-21. MR 0355289

[8] W. Sierpiński: Arytmetyka teoretyczna. Warszawa 1955. MR 0069191