Characterisation of bituminite and testing reproducibility of vitrinite and bituminite reflectance measurements in organic‑carbon-rich intervals of the Kimmeridge Clay Formation: ICCP Identification of Dispersed Organic Matter Working Group round robin exercises - J. Kus; A.G. Borrego; B. Bielowicz; P. Crosdale; M.-E. Damoulianou; D. Flores; C. Fonseca; P.A. Gonçalves; P.C. Hackley; M. Hámor-Vidó; S. Henne; B. Holstein; et al. (International Journal of Coal Geology, 2026)