Some properties of the multiplicity of a class of multivariate random processes are examined with particular emphasis on the derivation of a necessary and sufficient condition in order that the multiplicity of such a process be equal to one. Discussion is limited to processes with mutually orthogonal univariate components, but possible applications of the results to more general situations are suggested.
"On the Multiplicity of a Class of Multivariate Random Processes." Ann. Math. Statist. 43 (6) 2083 - 2089, December, 1972. https://doi.org/10.1214/aoms/1177690889