Schaff, Philip. History of the Christian Church (The Complete Eight Volumes in One). Amazon Kindle Edition, 2014.
Volume 2, Ante-Nicene Christianity A.D. 100-325, “Chapter 13. Ecclesiastical Literature of the Ante-Nicene Age, and Biographical Sketches of the Church Fathers.” sec. 159-204.
§ 171. Sixtus of Rome, also referred to as Sextus, bishop of Rome from around 119-128. Schaff identifies him as the sith bishop of Rome. He is thought to be the “author of a remarkable collection of moral and religious maxims” (Schaff 2014, loc. 21366). However, Jerome considered the attribution of the writing spurious, belonging rather to a Pythagorean named Xystus (Schaff 2014, loc. 21375). Others have attributed the work to a Quintus Sextus who was a Stoic philosopher. The writing never mentions Christ, so it has often been considered unlikely that any Christian, particularly a bishop, would write it (Schaff 2014, loc. 21384). Schaff makes a number of quotations (in Latin) to illustrate the flower of these maxims.