a production of WGBH Boston and WITF, Harrisburg; produced by Beth Hager and Randall MacLowry ; written by Ken Emerson and Randall MacLowry ; director, Randall MacLowry
a PBS digital presentation ; a Gemini Productions film for the WGBH/Nova Science Unit and Clear Blue Sky Productions ; written and directed by Gail Willumsen ; produced by Jill Shinefield, Gail Williamson
WGBH Educational Foundation ; produced and directed by Ben Loeterman ; written by Ben Loeterman and Alex Kotlowitz ; a Frontline coproduction with Ben Loeterman Productions, Inc