It's really not a rendering bug, you see. - Andrew Woo; Andrew Pearce; Marc J. Ouellette (IEEE Computer Graphics and Applications, 1996)

Approximating the Location of Integrand Discontinuities for Penumbral Illumination With Linear Light Sources. - Marc J. Ouellette; Eugene Fiume (Graphics Interface, 1999)

Approximating the Location of Integrand Discontinuities for Penumbral Illumination with Area Light Sources. - Marc J. Ouellette; Eugene Fiume (Rendering Techniques, 1999)

On numerical solutions to one-dimensional integration problems with applications to linear light sources. - Marc J. Ouellette; Eugene Fiume (ACM Trans. Graph., 2001)