Interlacing for weighted graphs using the normalized Laplacian. Butler, Steve — 2007 ELA. The Electronic Journal of Linear Algebra [electronic only]
A note on nested sums. Butler, Steve; Karasik, Pavel — 2010 Journal of Integer Sequences [electronic only]
Jumping sequences. Butler, Steve; Graham, Ron; Zang, Nan — 2008 Journal of Integer Sequences [electronic only]