http://watson.nci.nih.gov/bioc_mirror/packages/release/bioc/vignettes/GenomicFeatures/inst/doc/GenomicFeatures.pdf

http://www.bioconductor.org/packages/2.11/bioc/manuals/GenomicFeatures/man/GenomicFeatures.pdf

http://bioconductor.org/help/course-materials/2010/SeattleIntro/GenomicFeatures.pdf

Page 6 exactly what we need.

http://www.bioconductor.org/help/course-materials/2012/BioC2012/ranges.R

http://bioconductor.org/packages/release/bioc/vignettes/GenomicFeatures/inst/doc/GenomicFeatures.pdf