Esperantologio / Esperanto Studies. Nova Serio / New Series 1 (9) Tonkin Humphrey Heftet / 2020 / Esperanto
Gvidilo al la 17 Celoj por Daŭripova Evoluigo de Unuiĝintaj Nacioj (en Esperanto) Tonkin Humphrey Heftet / 2020 / Esperanto
Belarta Rikolto 2016 Premiitaj Verkoj de la Belartaj Konkursoj de Universala Esperanto-Asocio Tonkin Humphrey Heftet / 2016 / Esperanto
Rekomendata terminaro Esperanto-angla kaj angla-Esperanto por tradukantoj de oficialaj dokumentoj kaj gazetaraj komunikoj Recommended Esperanto-English and English-Esperanto Terminology for Translators of Official Documents and Press Releases Tonkin Humphrey Heftet / 2017 / Esperanto
Zamenhof The Life, Works and Ideas of the Author of Esperanto Tonkin Humphrey Heftet / 2010 / Engelsk
International Planned Languages. Essays on Interlinguistics and Esperantology Fiedler Sabine Heftet / 2018 / Engelsk
Language in the Twenty-First Century Selected papers of the millennial conferences of the Center for Research and Documentation on World Language Problems, held at the University of Hartford and Yale University Tonkin Humphrey Innbundet / 2003 / Engelsk
Language in the Twenty-First Century Selected papers of the millennial conferences of the Center for Research and Documentation on World Language Problems, held at the University of Hartford and Yale University Tonkin Humphrey Heftet / 2003 / Engelsk