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来源: www.rigb.org (The Royal Institution of Great Britain), www.iop.org (Institute of Physics), www.rsc.org (Royal Society of Chemistry), www.royalsociety.org (The Royal Society), www.sciencemuseum.org.uk (Science Museum, London), www.npg.org.uk (National Portrait Gallery), www.loc.gov (Library of Congress), www.jstor.org (JSTOR academic journal archives), www.archive.org (Internet Archive), www.ias.edu (Institute for Advanced Study), www.nhm.ac.uk (Natural History Museum), www.bl.uk (British Library), www.national-army-museum.ac.uk (National Army Museum), www.sciencehistory.org (Science History Institute)