Não informado. (1971). NLL Announcement Bulletin. National Lending Library for Science and Technology.
Chicago-referens (17:e uppl.)Não informado. NLL Announcement Bulletin. Boston, Inglaterra: National Lending Library for Science and Technology, 1971.
MLA-referens (8:e uppl.)Não informado. NLL Announcement Bulletin. National Lending Library for Science and Technology, 1971.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.