hiː pɹˈɑːbəbli ˈædᵻd tˈuː ʌvðə bˈʊks, wˌɪtʃ hæv tɹˈɪɡᵻz sˈɪɡnɪtʃɚɹ ɪn ɐ nˈiːt ɪtˈælɪk hˈænd, æt ðə tˈaɪm.
He probably added two of the books, which have Trigge's signature in a neat italic hand, at the time.