Source clustering in the Hi-GAL survey determined using a minimum spanning tree methodM. Beuret, N. Billot, L. Cambrésy, D. J. Eden, D. Elia, S. Molinari, S. Pezzuto and E. SchisanoA&A, 597 (2017) A114DOI: https://doi.org/10.1051/0004-6361/201629199