The April 28, 2009 FERC Cybersecurity Letter from FERC Chairman Jon Wellinghoff to Senator Edward J. Markey April 9, 2009 Press Release from Senator Edward J. Markey April 28, 2009 FERC Cybersecurity Letter to Senator Edward J. Markey April 28, 2009 The Honorable Edward J. Markey ChairmanSubcommittee on Energy and Environment Committee on Energy and…