@techreport{plt-tr2008-sgl-v4.1, author = {Scott Owens}, title = {{GL}: 3-D Graphics}, number = {PLT-TR2008-sgl-v4.1}, type = {Reference Manual}, institution = {PLT Scheme Inc.}, month = {August}, year = {2008}, url = {http://download.plt-scheme.org/doc/4.1/pdf/sgl.pdf}, note = {\url{http://plt-scheme.org/techreports/}} }