TY  - RPRT
TI  - Geometrical ray-tracing: a 'ray free' method.
AU  - A Ho
PY  - 1990
DO  - 10.1111/j.1475-1313.1990.tb00887.x
UR  - https://pubmed.ncbi.nlm.nih.gov/2263374/
ID  - 2263374
ER  -