The paper is mainly concerned with determining prior distributions on ignorance over parameter spaces, using invariance techniques similar to those of decision theory. Prior distributions are rarely determined exactly by such techniques and a number of less compelling methods for exact determination are given.
"Invariant Prior Distributions." Ann. Math. Statist. 35 (2) 836 - 845, June, 1964. https://doi.org/10.1214/aoms/1177703583