Timeline:
Danielson, Artificial Morality: Virtuous Robots for Virtual Games (1992)
Marsh, Formalizing Trust as a Computational Concept (1994)
Yudkowsky, Creating Friendly AI (2001)
Hall, Beyond AI: Creating the Conscience of a Machine (2007)
Wallach & Allen, Moral Machines: Teaching Robots Right from Wrong (2009)
Anderson & Anderson, eds., Machine Ethics (2011)
Lin, Abney, & Bekey, eds., Robot Ethics: The Ethical and Social Implications of Robotics (2011)
Bostrom, Intelligence Explosion: Groundwork for a Strategic Analysis (forthcoming) [mentioned here]
Timeline of book-length works in machine ethics
Timeline:
Danielson, Artificial Morality: Virtuous Robots for Virtual Games (1992)
Marsh, Formalizing Trust as a Computational Concept (1994)
Yudkowsky, Creating Friendly AI (2001)
Hall, Beyond AI: Creating the Conscience of a Machine (2007)
Wallach & Allen, Moral Machines: Teaching Robots Right from Wrong (2009)
Anderson & Anderson, eds., Machine Ethics (2011)
Lin, Abney, & Bekey, eds., Robot Ethics: The Ethical and Social Implications of Robotics (2011)
Bostrom, Intelligence Explosion: Groundwork for a Strategic Analysis (forthcoming) [mentioned here]