Honestly, your best first step might be a university library. You want to look for retired authors, people that had very successful careers and are no longer in

Honestly, your best first step might be a university library. You want to look for retired authors, people that had very successful careers and are no longer incentivized to keep a lid on their accumulated wisdom. Be wary of academic authors; I suspect there are exceptions but logically, if they could practice what they preached they probably wouldn't be in academics any more.