Jeker, Philipp, and Urs Krähenbühl. “Sulfur Profiles of the Twentieth Century in Peat Bogs of the Swiss Midlands Measured by ICP-OES and by IC”. CHIMIA, vol. 55, no. 12, Dec. 2001, p. 1029, https://doi.org/10.2533/chimia.2001.1029.