books.google.comhttp://books.google.com/books/about/The_practice_of_absorption_spectrophotom.html?id=oxc6AQAAIAAJ&utm_source=gb-gplus-shareThe practice of absorption spectrophotometry with Hilger instruments
The practice of absorption spectrophotometry with Hilger instruments: a guide to the technique of absorption measurement in the visible, ultra-violet, and infra-red regions of the spectrum