G. Pandey, S. Singh, and G. Hitkari, “Synthesis and characterization of polyvinyl pyrrolidone (PVP)-coated Fe3O4 nanoparticles by chemical co-precipitation method and removal of Congo red dye by adsorption process”, Int. Nano Lett., vol. 8, no. 2 (June 2018), May 2018, doi: 10.1007/s40089-018-0234-6.