Media type: E-Article Title: Artifacts and signs after a Vygotskian perspective: the role of the teacher Contributor: Mariotti, Maria Alessandra imprint: Springer Science and Business Media LLC, 2009 Published in: ZDM Language: English DOI: 10.1007/s11858-009-0199-z ISSN: 1863-9690; 1863-9704 Origination: Footnote: