@misc{indiciae0e084dd7bd04,
  title = {Pyrrolidone - a new solvent for the methylation of humic acid},
  author = {R.L. Wershaw and D.J. Pinckney and S.E. Booker},
  year = {1975},
  url = {https://pubs.usgs.gov/publication/70156691},
  note = {Source identifier: 70156691}
}