TY  - RPRT
TI  - On the Eigenfunctions and Eigenvalues of the General Linear Elliptic Differential Operator.
AU  - F E Browder
PY  - 1953
DO  - 10.1073/pnas.39.5.433
UR  - https://pubmed.ncbi.nlm.nih.gov/16589287/
ID  - 16589287
ER  -