The mass-radius relationship for very low mass stars: Four new discoveries from the HATSouth Survey

G. Zhou, D. Bayliss, J. D. Hartman, G. A. Bakos, K. Penev, Z. Csubry, T. G. Tan, A. Jordán, L. Mancini, M. Rabus, R. Brahm, N. Espinoza, M. Mohler-Fischer, S. Ciceri, V. Suc, B. Csák, T. Henning, B. Schmidt