Earlier linguists, such as André Martinet and Morris Swadesh, saw the potential of replacing glottalic sounds for the supposed plain voiced stops of Proto-Indo-European. The idea stayed hypothetical until more evidence for it was published in 1973 by Hopper in the journal "Glossa" and by Gamkrelidze and Ivanov in the journal "Phonetica".= = = Proto-Indo-Europeans = = =
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