References
Mark Siebel
with Wolff Werner (2008). Equivalent testimonies as a touchstone of coherence measures. Synthese, 161 (2), 167-182. https://doi.org/10.1007/s11229-006-9155-4.
(1997). Variation, derivability and necessity. Grazer Philosophische Studien, 53, 117-137. https://doi.org/10.5840/gps1997537.