Heviánková, S., M. Kyncl, and J. Kodymová. “STUDY AND RESEARCH ON CLEANING PROCEDURES OF ANAEROBIC DIGESTION PRODUCTS”. GeoScience Engineering, vol. 60, no. 4, Dec. 2014, pp. 39-50, https://geoscience.cz/ojs/index.php/GSE/article/view/62.