Wegler, U., B. G. Lühr, and A. Ratdomopurbo. “A Repeatable Seismic Source for Tomography at Volcanoes”. Annals of Geophysics 42, no. 3 (November 25, 1999). Accessed April 24, 2024. https://www.annalsofgeophysics.eu/index.php/annals/article/view/3736.