written and produced by Graham Chedd ; directed by Larry Engel ; a co-production of Chedd-Angier-Lewis Productions and Thirteen in association with WNET.ORG
written, produced and directed by John Rubin ; a production of NOVA and National Geographic Television in association with John Rubin Productions, Inc. ; WGBH Boston
directed and produced by Taggart Siegel ; produced by Teri Lang ; narrated & written by John Peterson ; produced in association with Independent Television Service (ITVS) ; produced by Collective Eye, Inc