Ramming, D; Bourdon, Roger J. (1989). "The pick operating system – a Practical Guide". Proceedings of the IEEE. 77 (2): 363. doi:10.1109/JPROC.1989.1203777. S2CID9328922.
Ramming, D; Bourdon, Roger J. (1989). "The pick operating system – a Practical Guide". Proceedings of the IEEE. 77 (2): 363. doi:10.1109/JPROC.1989.1203777. S2CID9328922.