The Buddha Before Buddhism: Wisdom from the Early Teachings: Amazon.co.uk: Gil Fronsdal: 9781611803242: Books is worth reading.
The Buddha Before Buddhism by Gil Fronsdal.
https://www.amazon.com/Buddha-before-Buddhism-Wisdom-Teachings/dp/1611803241/ref=sr_1_1?ie=UTF8&qid=1505681949
The Buddha before Buddhism: Wisdom from the Early Teachings https://www.amazon.com/dp/1611803241/ref=cm_sw_r_other_apa_1-qSybRCJTEYQ