J. Krumins, M. Klavins, R. Krukovskis, A. Viksna, and L. Busa, “THE EVALUATION OF STABLE ISOTOPIC RATIOS 13C AND 15N IN HUMIC ACIDS ALONG A FEN PEAT PROFILE”, ETR, vol. 1, pp. 123–126, Jun. 2019, doi: 10.17770/etr2019vol1.4127.