doi          = "10.1145/1787234.1787255",
 doi          = "10.1109/2.546611",
 doi          = "10.1145/325096.325100",
 doi          = "10.1007/978-3-642-28869-2\_2",
 doi          = "10.1145/1925844.1926394",
 doi          = "10.1145/1375581.1375591",
 doi          = "10.1145/1480881.1480930",
 doi          = "10.1007/978-3-642-11957-6\_10",
 doi          = "10.1007/978-3-642-11970-5\_7",
 doi          = "10.1145/325164.325102",
 doi          = "10.1109/TC.1979.1675439",
 doi          = "10.1145/1040305.1040336",
 doi          = "10.1109/12.752664",
 doi          = "10.1145/1993498.1993520",
 doi          = "10.1145/1785414.1785443",