He was elected member of several foreign academies and societies, including the Royal Danish Academy of Sciences and Letters in 1980, the Norwegian Academy of Science and Letters in 1983, the American Academy of Arts and Sciences in 1989, the London Mathematical Society in 1994, the Canadian Academy of Sciences in 1995 (incorporated since 2002 in the Royal Society of Canada), the US National Academy of Sciences in 1997, the Russian Academy of Science in 2003 and the Royal Academy of Science, Letters and Fine Arts of Belgium in 2016.
hiː wʌz ᵻlˈɛktᵻd mˈɛmbɚɹ ʌv sˈɛvɹəl fˈɔːɹən ɐkˈædəmiz ænd səsˈaɪəɾiz, ɪŋklˈuːdɪŋ ðə ɹˈɔɪəl dˈeɪnɪʃ ɐkˈædəmi ʌv sˈaɪənsᵻz ænd lˈɛɾɚz ɪn nˈaɪntiːnhˈʌndɹɪd ˈeɪɾi, ðə noːɹwˈiːdʒən ɐkˈædəmi ʌv sˈaɪəns ænd lˈɛɾɚz ɪn nˈaɪntiːnhˈʌndɹɪd ˈeɪɾi θɹˈiː, ðɪ ɐmˈɛɹɪkən ɐkˈædəmi ʌv ˈɑːɹts ænd sˈaɪənsᵻz ɪn nˈaɪntiːnhˈʌndɹɪd ˈeɪɾi nˈaɪn, ðə lˈʌndən mˌæθɪmˈæɾɪkəl səsˈaɪəɾi ɪn nˈaɪntiːnhˈʌndɹɪd nˈaɪnti fˈoːɹ, ðə kɐnˈeɪdiən ɐkˈædəmi ʌv sˈaɪənsᵻz ɪn nˈaɪntiːnhˈʌndɹɪd nˈaɪnti fˈaɪv ɪŋkˈoːɹpɚɹˌeɪɾᵻd sˈɪns tˈuː θˈaʊzənd tˈuː ɪnðə ɹˈɔɪəl səsˈaɪəɾi ʌv kˈænədə, ðə jˌuːˈɛs nˈæʃənəl ɐkˈædəmi ʌv sˈaɪənsᵻz ɪn nˈaɪntiːnhˈʌndɹɪd nˈaɪnti sˈɛvən, ðə ɹˈʌʃən ɐkˈædəmi ʌv sˈaɪəns ɪn tˈuː θˈaʊzənd θɹˈiː ænd ðə ɹˈɔɪəl ɐkˈædəmi ʌv sˈaɪəns, lˈɛɾɚz ænd fˈaɪn ˈɑːɹts ʌv bˈɛldʒəm ɪn tˈuː θˈaʊzənd sˈɪkstiːn.