All truth finds its origin in God Himself. Therefore, we should not be dismayed that Jude quotes from sources not inspired by God. We can be sure Jude, under the superintendence of the Holy Spirit, was able to sift the wheat from the chaff in these non-canonical sources. Thus his letter, like all of Scripture, remains authoritative. Thank the Lord for giving us His Word and study it so that you may apply its truth to your life.