doi          = {10.1007/s00236-009-0095-6},
 doi          = {10.3233/FI-2011-606},
 doi          = {10.1007/978-3-642-29709-0\_1},
 doi          = {10.1007/978-3-319-04921-2\_13},
 doi          = {10.1007/978-3-319-07734-5\_7},
 doi          = {10.1007/978-3-642-38143-0\_5},
 doi          = {10.1007/978-3-642-36742-7\_9},
 doi          = {10.1007/BF00289519},
 doi          = {10.1109/3468.553226},