An Original Source Containing the Sermon of St. Leonard of Port Maurice: The Little Number of Those Who are Saved

This rather famous homily of the eighteenth century Franciscan is rather easy to come by on the internet; for example, see https://www.saintsbooks.net/books/St.%20Leonard%20of%20Port%20Maurice%20-%20The%20Little%20Number%20of%20Those%20Who%20Are%20Saved.pdf However, I have not been able to find a book from which this sermon was extracted; nor, have any of those that have posted this indicated the "ancient" source from which the sermon (now presented in modern English is derived.) After the end of the sermon, the above link, for example, indicates "This sermon by Saint Leonard of Port Maurice was preached during the reign of Pope Benedict XIV, who so loved the great missionary." QUESTION: Can anyone cite an original source (an archived old book, perhaps) which contains this sermon of St. Leonard of Port Maurice? Thank you.