@article{MAN_1970__189_162076,
     author = {M. NAKAI and L. SABIO},
     title = {A {New} {Operator} for {Elliptic} {Equations,} and the {P-compactification} for ...u = {P} u.},
     journal = {Mathematische Annalen},
     pages = {242--256},
     publisher = {mathdoc},
     volume = {189},
     year = {1970},
     url = {http://geodesic.mathdoc.fr/item/MAN_1970__189_162076/}
}