text: *PDB molecule of the month:
  **[http://www.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb72_1.html ATP synthase] 
  **[http://www.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb36_1.html Cytochrome c] 
  **[http://www.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb5_1.html Cytochrome c oxidase] 
  *Interactive molecular models at Universidade Fernando Pessoa:
  **[https://web.archive.org/web/20090112031333/http://www2.ufp.pt/~pedros/anim/2frame-ien.htm NADH dehydrogenase]
  **[https://web.archive.org/web/20090111212436/http://www2.ufp.pt/~pedros/anim/2frame-iien.htm succinate dehydrogenase]
  **[https://web.archive.org/web/20090112035125/http://www2.ufp.pt/~pedros/anim/2frame-iiien.htm Coenzyme Q - cytochrome c reductase]
  **[https://web.archive.org/web/20090111220321/http://www2.ufp.pt/~pedros/anim/2frame-iven.htm cytochrome c oxidase]