00369nam a22001457a 450000500170000008200120001710000180002924500360004726000350008330000080011849000430012650500300016965000150019965000090021420250818101114.0  a530 PER  aPerera,V.P.S.  aGeometrical and Physical Optics  aColombobOpen Universityc2010  a46p  aFaculty of Natural Sciences-  PYU 2261  aBachelor Science :Level 4  a chemistry  aOUSL