Anderson, T. W., Olkin, I. (1985): Maximum-likelihood estimation of the parameters of a multivariate normal distribution. Linear Algebra and its Applications 70: 147-–171.
Filipiak, K., John, M., Markiewicz, A. (2020): Comments on Maximum Likelihood Estimation and Projections Under Multivariate Statistical Models. In: Holgersson, T., Singull, M. (eds), Recent Developments in Multivariate and Random Matrix Analysis, 51—66. Springer International Publishing, Cham.
Filipiak, K., Markiewicz, A., Mieldzioc, A., Sawikowska, A. (2018): On Projection of a Positive Definite Matrix on a Cone of Nonnegative Definite Toeplitz Matrices. The Electronic Journal of Linear Algebra 33: 74—82.
Ohlson M., von Rosen D. (2010): Explicit estimators of parameters in the Growth Curve model with linearly structured covariance matrices. Journal of Multivariate Analysis 101: 1284—1295.
Szatrowski, T.H. (1980): Necessary and sufficient conditions for explicit solutions in the multivariate normal estimation problem for patterned means and covariances. The Annals of Statistics 8(4): 802–810.