Paetzold, M., Andert, T., Hahn, M., Asmar, S. W., Barriot, J.-P., Bird, M. K., et al. (2016). A homogeneous nucleus for comet 67P/Churyumov-Gerasimenko from its gravity field. Nature, 530(7588), 63-65. doi:10.1038/nature16535.