Orthodox Study Bible: The Orthodox Study Bible includes a ton of foot notes that are in line with the Holy Tradition of the Church. It is a great resource that is available in print as well as a phone app version.  I would recommend both, the print version for your home and the mobile version so you always have a copy with you.

Didache: A short booklet on church practices written by an anonymous source written at the end of the first century. When looking at holy tradition (teachings) some people like to question the ability for spoken word to be transmitted from generation to generation. Well the Didache was lost for centuries and in 1873 a copy was found that was dated from 1056. A fascinating document that accounts for successful transmission of spoken tradition it includes instructions on baptism, prayer and fasting on Wednesdays/Fridays, which the Orthodox Church still adheres to today.

Writings of Polycarp: Polycarp is one of the three earliest writings we have after the Bible and the Didache from the early church (the other two being St. Ignatius and St. Clement). Trained by St. John the Apostle he was martyred in 155 A.D. by knife after surviving burning. His writings are short but the account of his martyrdom is worth a read. An incredible story of the earliest most reliable account of a martyrdom after the Bible.

St. Ignatius: The Epistles: St. Ignatius is one of the three earliest Christian writers not included in the bible. His letters are written in the early 2nd century on his way to Rome to be martyred. As I member of the laity I found his letters some of the most interesting of the Apostolic fathers as he spoke looking forward to giving his life for Christ and continuing to each about Christianity despite an imminent death. Holy tradition tells us that St. Ignatius is the child referenced in the Bible in Mark 9:36-37, as well as an apostle of St. John. Around the year 108 A.D. he was martyred by lions in the Circus Maximus

      An explanation of his letters can be found in the book: Bearing God: The Life and Works of St. Ignatius of Antioch

Clement of Rome: One of the earliest writings or possibly the earliest from the church (from the 1st century) not included in the Bible (along with St. Ignatius and St. Polycarp). Some early list of biblical books have his writings included as part of the New Testament canon. Written in the first century he is likely the first Bishop of Rome (what the Catholics would call Pope) after the Apostle Peter. His writings often talk about the role of the priest and their role in the Church. He is mentioned by Peter as a co-worker in the Bible (Philippians 4:2-3) and was ultimately martyred around 99 A.D. by being tied to an anchor then thrown into the sea. .

Against Heresies by Irenaeus: Have you ever heard the saying that “There are no new heresies”, they are just repackaged versions of old ones. I would argue that if that statement is true, the apology (defense) against heresies was already written in the 2nd Century. As a 21st Century reader it felt like St. Irenaeus’ books “Against Heresies” was answering questions that wouldn’t be popular for another 1600 years. The first two books of On Heresies focus largely on the Gnostic heresies, but the last three books remain relevant today as they did when they were written. If you want to written evidence that the Orthodox faith remains unchanged this book is proof that Orthodoxy is still adhering to the faith received from Christ and passed through apostolic succession to modern times.