TRUST - I. A 3D externally illuminated slab benchmark for dust radiative transferK. D. Gordon, M. Baes, S. Bianchi, P. Camps, M. Juvela, R. Kuiper, T. Lunttila, K. A. Misselt, G. Natale, T. Robitaille and J. SteinackerA&A, 603 (2017) A114DOI: https://doi.org/10.1051/0004-6361/201629976