sˈɛvɹəl jˈɪɹz lˈeɪɾɚ, hiː ˈɔfɚd ɐ nˈʌmbɚɹ ʌv lˈɛksɪkəl ænd fˌɑːnəlˈɑːdʒɪkəl kˌɔːɹɪspˈɑːndənsᵻz bᵻtwˌiːn ðə nˈɔːɹθ kɔːkˈeɪʒən, sˈælɪʃən, ænd wˈækæʃən lˈæŋɡwɪdʒᵻz, kəŋklˈuːdɪŋ ðæt sˈælɪʃən ænd wˈækæʃən mˈeɪ ɹˌɛpɹᵻzˈɛnt ɐ dɪstˈɪŋkt bɹˈæntʃ ʌv nˈɔːɹθ kɔːkˈeɪʒən ænd ðæt ðɛɹ sˌɛpɚɹˈeɪʃən fɹʌm ɪt mˈʌst poʊstdˈeɪt ðə dˌɪsəlˈuːʃən ʌvðə nˈɔːɹθiːst kɔːkˈeɪʒən jˈuːnɪɾi ˈævɑːɹɹˈænditsˈɛziən, wˌɪtʃ tˈʊk plˈeɪs ɚɹˈaʊnd ðə sˈɛkənd ɔːɹ θˈɜːd mɪlˈɛniəm bˌiːsˈiː.
Several years later, he offered a number of lexical and phonological correspondences between the North Caucasian, Salishan, and Wakashan languages, concluding that Salishan and Wakashan may represent a distinct branch of North Caucasian and that their separation from it must postdate the dissolution of the Northeast Caucasian unity (Avar-Andi-Tsezian), which took place around the 2nd or 3rd millennium BC.