TY  - GEN
AU  - Gunasinghe , R.M.
AU  - Liyanage , L.S.G.
AU  - Tennakoone , M.M.S.G.K.
AU  - Sumanasekara , G.U.
TI  - Physics geometrical optics
U1  - 535.32 
PY  - 1986///
CY  - Nugegoda
PB  - Open University
KW  - Physics
ER  -