text: Atomic energy-level and Grotrian diagrams by Stanley Bashkin and John O. Stoner, Jr.
  * [https://www.osti.gov/etdeweb/biblio/7245253 Volume I: Hydrogen - Phosphorus]
  * [https://www.osti.gov/etdeweb/biblio/5726087 Volume I: Hydrogen - Phosphorus (Addenda)]
  * [https://www.osti.gov/etdeweb/biblio/5286863 Volume III]
  * [https://www.osti.gov/etdeweb/biblio/7095470 Volume IV]