Yasushi Umeda Tetsuo Tomiyama Hiroyuki Yoshikawa Yoshiki Shimomura Using Functional Maintenance to Improve Fault Tolerance. 25-31 1994 9 IEEE Expert 3 http://csdl.computer.org/comp/mags/ex/1994/03/x3025abs.htm db/journals/expert/expert9.html#UmedaTYS94