The use of the words 'Workshop of' followed by an artist's name guarantees that the work was executed in the studio of the cited master or under their direction. When a studio is mentioned, it must be followed by an indication of the period if it is a family workshop that has retained the same name over several generations. - see article 5 of Decree no. 81-255 of 3 March 1981 on the repression of fraud in transactions of works of art and collectors' items.