1. AIS 20: Functionality Classes and Evaluation Methodology for Deterministic Random Number Generators. Version 1 (02.12.1999) (mandatory if a German IT security certificate is applied for; English translation) (1999),
www.bsi.bund.de/zertifiz/zert/interpr/ais20e.pdf
2. AIS 31: Functionality Classes and Evaluation Methodology for Physical Random Number Generators. Version 1 (25.09.2001) (mandatory if a German IT security certificate is applied for; English translation) (2001),
www.bsi.bund.de/zertifiz/zert/interpr/ais31e.pdf
3. ANSI X9.82, Random Number Generation (Draft Version)
4. Lecture Notes in Computer Science;V. Bagini,1999
5. Bucci, M., Germani, L., Luzzi, R., Trifiletti, A., Varanonuovo, M.: A High-Speed Oscillator-Based Truly Random Number Source for Cryptographic Applications. IEEE Trans. Computers 52, 403–409 (2003)