Eugene H. Wolf Local loop ISDN dial backup for frame relay. 70-74 1998 8 Int. Journal of Network Management 2 http://dx.doi.org/10.1002/(SICI)1099-1190(199803/04)8:2<70::AID-NEM257>3.0.CO;2-B db/journals/ijnm/ijnm8.html#Wolf98