1965 - James Gunn[?] and Bruce Peterson[?] use observations of the relatively low absorption of the blue component of the Lyman-alpha line[?] from 3C9[?] to strongly constrain the density and ionization state of the intergalactic medium
... in their traditional order: vowels, stops and nasals (starting in the back if the mouth and moving forward), and finally the liquids[?] and sibilants.
(Note: The long ...