PEŃA-MÉNDEZ, E. M., Dagmar GAJDOŠOVÁ, Klára NOVOTNÁ, Pavel PROŠEK and
Josef HAVEL. Mass Spectrometry of Humic Substances of different origin including those from Antarctica. A Comparison Study.
Talanta. Elsevier Science, 2005, vol. 67, No 5, p. 870-890. ISSN 0039-9140.