@article{10_1017_S0017089500002779,
     author = {Heersink, Rudolf},
     title = {Characterization of certain differential operators in the solution of linear partial differential equations{\textdagger}},
     journal = {Glasgow mathematical journal},
     pages = {83--88},
     year = {1976},
     volume = {17},
     number = {2},
     doi = {10.1017/S0017089500002779},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500002779/}
}