Acciari, V., Ansoldi, S., Antonelli, L., Engels, A., Baack, D., Babic, A., Banerjee, B., Barres de Almeida, U., Barrio, J., Becerra Gonzalez, J., Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O.,...Bonnoli, G. (2020) Unraveling the Complex Behavior of Mrk 421 with Simultaneous X-Ray and VHE Observations during an Extreme Flaring Activity in 2013 April*. ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES , 248(2).