Evelyne Barbin was previously a professor of epistemology and history of sciences at the University of Nantes (France). Since 2014, she is now professor emeritus at the University of Nantes. She is a member of the Laboratory of Mathematics Jean Leray CNRS UMR 6629, where she is in charge of the research group on history of mathematics. She taught history of mathematics and sciences in all levels of teaching from licence to master. She was the director of 15 theses on the history of mathematics and sciences. Her research concerns three fields: history of mathematics, history of mathematics teachings, and relations between history and teaching of mathematics. The main themes of her historical research are: mathematical proofs in history, mathematics and sciences in the 17th and 19th centuries, and history of mathematics teaching from the 19th to the 20th century. She has worked at the IREM (Institute for Research on Mathematics Education) since 1975. As convenor of the National Committee of the IREM “Epistemology and History of Mathematics”, she has organized 20 national colloquia, 8 interdisciplinary Summer Universities on history and teaching mathematics, and the first European Summer University (ESU) "Epistemology and History in Mathematics Education" in 1993. She was chair of seven ESUs from 1996 to 2014. Since 1980, she has also been a member of the International Study Group on the Relations between History and Pedagogy of Mathematics (HPM). She was the chair of HPM from 2008 to 2012. Marta Menghini is an associate professor in the Department of Mathematics of the University of Rome Sapienza. She is the author of numerous published works in the fields of Mathematics Education, History of Mathematics, and the History of Mathematics Education. She was in the Scientific Committee and chaired the Organizing Committee of the International Symposium held in Rome in March 2008, “The First Century of the InternationalCommission on Mathematical Instruction: Reflecting and Shaping the World of Mathematics Education”, and edited the volume published on this occasion by Enciclopedia Italiana. In 2012, she held a Regular Lecture at ICME 12 in Seoul. She wrote, with Evelyne Barbin, the Chapter on “History of Teaching Geometry” in the International Handbook on the History of Mathematics Education. She was involved in the translation of Felix Klein’s third volume on “Elementary Mathematics from a Higher Standpoint”, which appeared in 2016. Klaus Volkert is a full professor at the University of Wuppertal; he lectures on mathematics, didactics, and history. His interests are mainly in the history of geometry and topology, and recently he started a project on Wilhelm Fiedler. He is Editor in Chief of the journal “Mathematische Semesterberichte” (together with J. Steuding) and editor of the series “Mathematik im Kontext” (with David Rowe).