Reply to Engelder: Potential for fluid migration from the Marcellus Formation remains possible

N. R. Warner, R. B. Jackson, T. H. Darrah, S. G. Osborn, A. Down, K. Zhao, A. White, A. Vengosh
2012 Proceedings of the National Academy of Sciences of the United States of America  
doi:10.1073/pnas.1217974110 fatcat:y2l7xx36tzbu7d3w6mlzbc7t3i