ProQuest. (2004). ProQuest Science Journals. USA: Umi company.
Chicago Style aipamenaProQuest. ProQuest Science Journals. USA: Umi company, 2004.
MLA aipamenaProQuest. ProQuest Science Journals. USA: Umi company, 2004.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.