@INPROCEEDINGS{Annen:EGSR:2004,
  AUTHOR = 	{Annen, Thomas and Kautz, Jan and Durand, Frédo and Seidel, Hans-Peter},
  EDITOR = 	{Keller, Alexander and Jensen, Henrik Wann},
  TITLE = 	{Spherical Harmonic Gradients for Mid-Range Illumination},
  BOOKTITLE = 	{Rendering Techniques 2004 : Eurographics Symposium on Rendering},
  PUBLISHER = 	{Eurographics},
  YEAR = 	{2004},
  ORGANIZATION = 	{Eurographics Association},
  PAGES = 	{331--336},
  ADDRESS = 	{Norrk{\"o}ping, Sweden},
  MONTH = 	{June},
  ISBN = 	{3-905673-12-6},
}