1. Petrographie du kerogene;Alpern,1980
2. Methods for microscopical determination of the reflectance of coal macerals. Standard AS 2486-1989;Australian Standard,1989
3. An update on the suppression of vitrinite reflectance;Barker;TSOP Newsletter,1991
4. Analyses of coal from the Ferron Sandstone Member of the Mancos Shale near Emery, Utah. USGS OF-2004-1279;Barker,2004
5. An empirical determination of the minimum number of measurements needed to estimate the mean random vitrinite reflectance of disseminated organic matter;Barker;Organic Geochemistry,1993