Everything that is learned about leadership simply indicates that there is always more to learn. It is amazing to consider the amount of information readily accessible.
Where do leaders turn?
First, turn to God. The best leadership book available is the Bible.
Second, turn to other godly leaders. Seek their help and learn from their wisdom.
Third, turn inward for reflection. Many answers can be found by reflecting on how God has worked throughout the journey to bring us where we are as leaders.
This does not exhaust the possibilities, but it does provide a few steps in benefiting from each learning moment.