hiː kˈælkjʊlˌeɪɾᵻd ðə dˌɪfɚɹˈɛnʃəl ɪnðɪ ˈæɾɪjəhˈɜːzɪbɹˌʌtʃ spˈɛktɹəl sˈiːkwəns ɪn kˈeɪθˈiəɹi ænd kˈɑːmplɛks kˈɑːboːɹdˌɪzəm θˈiəɹi, kənstɹˈʌktᵻd tʃˈɜːndˈoʊld kˈæɹɪktɚz ænd ðə jˌuːnɪvˈɜːsəl tˈɑːd dʒˈɛnəs ɪn kˈɑːboːɹdˌɪzəm, ænd ɡˈeɪv ɐn ɔːltˈɜːnətˌɪv ɪfˈɛktɪv səlˈuːʃən ʌvðə mˈɪlnɚhˈɜːzɪbɹˌʌtʃ pɹˈɑːbləm.
He calculated the differential in the Atiyah-Hirzebruch spectral sequence in K-theory and complex cobordism theory, constructed Chern-Dold characters and the universal Todd genus in cobordism, and gave an alternative effective solution of the Milnor-Hirzebruch problem.