In the mid-1970s,[30] while a post-doctoral fellow,[31] he began to take a particular interest in energy in his writing.[3] Basing the book on four years of research, with Robert B. Stobaugh he co-authored and co-edited Energy Future: The Report of the Energy Project at the Harvard Business School in 1979.[30] According to the Los Angeles Times, the book "caused a considerable stir with its optimistic view of the possibilities of energy conservation and such alternative sources as solar power."[4] It proved to be a The New York Times bestseller,[30] ultimately selling 300,000 copies in six languages.[5] Within its first year of release, Yergin and Stobaugh were called to Washington, D.C. several times to testify before Congressional committees.[30] He also advised James Schlesinger, the first US energy secretary, around the time of the Iranian revolution.