TY  - BOOK
AU  - Welford,W.T.
TI  - Geometrical optics: optical instrumentation 
T2  - Undergraduate textbooks in physics
PY  - 1962///
CY  - Amsterdam
PB  - North-Holland Pub. Co.
KW  - Geometrical optics
KW  - Optical instruments
N1  - Includes index; Includes bibliographical references
ER  -