@ARTICLE{koch-etal_10,
  author = {Koch, K.R. and H. Kuhlmann and W.-D. Schuh},
  title = {Approximating covariance matrices estimated in multivariate models
	by estimated auto- and cross-covariances},
  journal = {J. Geodesy},
  year = {2010},
  volume = {84},
  pages = {383--397},
  number = {6},
  doi = {10.1007/s00190-010-0375-5}
}