I'm not too familiar with the church fathers. But I wouldn't accept anything - either written or spoken - if it contradicts the Bible, because the testimony of the Apostles and Prophets is true and complete. I also think you can sense how you feel in your spirit about a document. If there is something "off" about a piece of literature, the Holy Spirit may give you a slightly uncomfortable feeling about it. It's important not to ignore either of these two methods of being led by the Spirit: first and foremost, the BIBLE; and secondly, the INNER WITNESS OF THE HOLY SPIRIT in your spirit if you've been born again. If you ignore a prompting to avoid a manuscript, you might end-up reading something that could negatively affect your mind for quite some time, until you are brought back to the witness of the Bible and to the inner witness of the Spirit. Other times, even though the Bible is complete in every aspect, the Holy Spirit may genuinely lead you to some beneficial statements written by other men of God. So if we're sincere, we'll know whether the Holy Spirit is approving of our choice to read something.