For which instrument did this German composer write a textbook, whose portrait was painted by Pietro Lorenzoni in 1765?
Pietro Antonio Lorenzoni: Pietro Antonio Lorenzoni (1721–1782) was an Italian painter who is believed to have painted several portraits of Wolfgang Amadeus Mozart and his family: "The Boy Mozart" (1763), his sister Maria Anna Mozart in "Nannerl as a Child" (1763) and a portrait of their father Leopold Mozart (c. 1765). Leopold Mozart:  Mozart is best known today as the father and teacher of Wolfgang Amadeus Mozart, and for his violin textbook "Versuch einer gründlichen Violinschule".
i don't know