A. Barabasi, Z. Dezso, E. Ravasz, S. Yook, and Z. Oltvai. On Barabasi's personal website (http://www.nd.edu/~alb/html/publications.html) from Modeling of Complex Systems: Seventh Granada Lectures, (2002)
{. Barabasi, Z. Dezso, E. Ravasz, {. Yook, and Z. Oltvai. Modeling of Complex Systems: Seventh Granada Lectures, 661, page 1--16. Melville, NY, American Institute of Physics, (2003)