@article{834106, author = {James Butler and B. Johnson and R Barnes}, title = {Radiometric Measurement Comparisons at NASA's Goddard Space Flight Center: Part II. Irradiance Lamp Comparisons and the NIST Sphere Source}, year = {2002}, number = {14}, month = {2002-07-01 00:07:00}, publisher = {The Earth Observer}, language = {en}, }