[1] Library of Congress, <http://international.loc.gov/intldl/intldlhome.html>.
 
[2] Desire, <http://www.desire.org/html/subjectgateways/subjectgateways.html>.
 
[3] TERENA, <http://www.terena.nl/library/gnrt/websearch/gateways.html>.
 
[4] National Library of Australia (NLA), <http://www.nla.gov.au/initiatives/sg/ index.html>. 

[5] PINAKES, <http://www.hw.ac.uk/libWWW/irn/pinakes/pinakes.html>.
 
[6] ROADS, <http://www.ukoln.ac.uk/metadata/roads/what/>.
 
[7] John Kirriemuir et al. Cross-searching subject gateways. «D-Lib Magazine». <http://www.dlib.org/dlib/january98/01kirriemuir.html>.
 
[8] Magda Heiner-Freiling. Survey on subject heading languages used in national libraries and bibliographies. «Classification and Cataloging Quarterly», v. 29, no. 1/ 2 (2000), p. 189-198.
 
[9] Barbara Tillett. A virtual international authority file (VIAF). In: Record of a workshop on Authority Control among Chinese Korean and Japanese Languages (CJK Authority 3), marzo 2002, p. 117-139.
 
[10] MACS, <http://infolab.kub.nl/prj/macs/>.