@article{lorch:1963:hmp,
    author = {Lorch, Lee and Szego, Peter},
     title = {Higher monotonicity properties of certain {S}turm-{L}iouville
              functions.},
   journal = {Acta Math.},
  fjournal = {Acta Mathematica},
    volume = {109},
      year = {1963},
     pages = {55–73},
      issn = {0001-5962},
   mrclass = {34.30},
  mrnumber = {MR0147695 (26 \#5209)},
mrreviewer = {G. Sansone},
       doi = {10.1007/BF02391809},
     zblno = {0111.06502}}