1. Alberani, V. (1992), La Letteratura Grigia. Guida per le Biblioteche Speciali e i Servizi d’Informazione, La Nuova Italia Scientifica, Rome.
2. Carrol, B.C. and Cotter, G.A. (1994), “A new generation of grey literature: the impact of advanced information technologies”, in First International Conference on Grey Literature, 13‐15 December 1993, Organising Bureau, Amsterdam, pp. 5‐17.
3. Committee on Scientific and Technical Information (COSATI), (1996), Standard for Descriptive Cataloguing of Government Scientific and Technical Reports.(AD 641091/PB 173‐314).
4. Di Cesare, R. (1993), “The evaluation of GL impact in physical sciences using bibliometric indicators: preliminary results”, in First International Conference on Grey Literature, Amsterdam, 13‐15 December, Organising Bureau, Amsterdam, pp. 64‐75.
5. Draper, M. (1994), Talk given at the APS Workshop, in http://publish.aps.org/EPRINT/KATHD/draper.tml.