The Nuttall Encyclopedia
The name given to the sacred writings of the Guebres or Parsees, ascribed to Zoroaster, of which he was more the compiler than the author, and of which many are now lost; they represent several stages of religious development, and as a whole yield no consistent system.
Wood, James, ed. Entry for 'Zend-Avesta'. The Nuttall Encyclopedia. https://www.studylight.org/encyclopedias/eng/nut/z/zend-avesta.html. Frederick Warne & Co Ltd. London. 1900.