The Apostle Lectionary, written on parchment in the second half of the 13th century, is one of the important linguistic sources delimiting the early (Preslav) from the later (Athonite) redaction of this liturgical book. The lectionary contains the portions of scripture, the lessons, to be read at divine service on particular days of the church calendar. This manuscript is remarkable for the completeness of the readings from the Acts of the Apostles and the Epistles, and for its detailed menologion, a monthly calendar indicating the feast days of saints that was very important for mediaeval Bulgarian religious culture and history.