@incollection{berry:1980:co,
    author = {Berry, M. V. and Upstill, C.},
     title = {Catastrophe optics: Morphologies of caustics and their
              diffraction patterns},
 booktitle = {Progress in Optics},
    editor = {Wolf, E.},
   address = {Amsterdam},
 publisher = {North-Holland},
    volume = {18},
      year = {1980},
     pages = {257–346}}