Cheng, L. et al. 2015. Hydrothermal Synthesis of Birnessite-Type Potassium Manganese Oxide and its Application as Lubricant in Liquid Paraffin. Asian Journal of Chemistry. 28, 4 (Dec. 2015), 883–887. DOI:https://doi.org/10.14233/ajchem.2016.19544.