text: * R: (:ja:理科年表): An (mostly) annual reference book published in Japan since 1925CE. Note that the actual published year is typically one year earlier than the nominal (book title) year.
  </references>
  * I: : Revised roughly by each decade. First edition 1935CE.
  </references>
  *D: Kyoritsu Great Dictionary of Chemistry
  </references>
  *X: Other usage examples
  </references>