E. Kriswati, I. Meilano, S. Suhartaman, Y. Suparman, H. Z. Abidin, and T. Sinaga, “Characteristic of Lokon Volcano Deformation of 2009 - 2011 Based on GPS Data”, Indonesian J. Geosci., vol. 7, no. 4, pp. 199–209, Dec. 2012.