@ARTICLE{sanso-schuh_87,
  author = {Sans\`{o}, F. and Schuh, W.-D.},
  title = {Finite covariance functions},
  journal = {Bulletin G\'{e}od\'{e}sique},
  year = {1987},
  volume = {61},
  pages = {331--347},
  number = {4},
  doi = {10.1007/BF02520559}
}