science fiction publishing figures who have worked at Ace include Tom Doherty, who left to start Tor Books, and Jim Baen, who left to work at Tor and who eventually founded Baen Books. Writers who have worked at Ace include Frederik Pohl and Ellen Kushner. In 1996, Penguin Group (USA) acquired the Putnam Berkley Group, and has retained Ace as its science fiction imprint. As of December 2012, recently published authors included Joe Haldeman, Charles Stross, Laurell K. Hamilton, Alastair Reynolds, and Jack McDevitt. Penguin merged with Random House in 2013 to form Penguin Random House, which continues to own Berkley. Ace's editorial team is also responsible for the Roc Books imprint, although the two imprints maintain a separate identity. People The following people have worked at Ace Books in various editorial roles. The list is sorted in order of the date they started working at Ace, where known. It includes editors who are notable for some reason, as well as the most recent editors at the imprint. A. A. Wyn, owner (1952–1967) Donald A. Wollheim, editor (1952–1971) Terry Carr, editor (1964–1971); freelance editor (1983–1987) Pat LoBrutto, mail room (1969–1972); science fiction editor (1974–1977) Frederik Pohl, executive editor (December 1971 – July 1972) Tom Doherty, publisher (1975–1980) Jim Baen, complaints department (c. 1973–1974); gothics editor (c. 1974); science fiction editor (c. 1977–1980) Ellen Kushner Terri Windling, editor (1979–1987) Harriet McDougal, editorial director Susan Allison, editor (1980–1982); editor-in-chief (1982–2006); vice president (1985 – July 2015) Beth Meacham, editorial assistant (1981–1982); editor (1982–1983) Ginjer Buchanan, editor (1984–1987); senior editor (1987–1994); executive editor, science fiction and fantasy (1994 – January 1996); senior executive editor and marketing director (January 1996 – 2006); editor-in-chief (2006–2014). Peter Heck (c. 1991–1992) Laura Anne Gilman (c. 1991) Lou Stathis, editor (? – c. 1994) Anne Sowards, editorial assistant/associate editor (1996–2003); editor (2003 – February 2007), senior editor (from February 2007), executive editor (by September 2010) Ace nomenclature Until the late 1980s, Ace titles had two main types of serial numbers: letter series, such as "D-31" and "H-77", and numeric, such as "10293" and "15697". The letters were used to indicate a price. The following is a list of letter series with their date ranges and prices. D-series: 35¢, 1952 to 1962. S-series: 25¢, 1952 to 1956. T-series: 40¢. This series is listed in Tuck's Encyclopedia, but he gives no examples in his index and there are none cited