I would have recommended the same books.
In addition to that please read Books by Peter F Drucker on Management, strategy and how to treat Humans.
In startups, human interaction is most important more so than a huge corporation because both employee and employer needs to understand the importance of each other. Make sure you treat them right and make sure they are excited,valued and well treated.
Get a mentor, you need to keep them engaged, request with specific questions, ask for suggestions. No one wants to receive a specific mail asking me to be a mentor. they would rather send a note/ give a suggestion which will help you.
All the very best for you and company, and keep us posted on how your journey is.
One of my favorite books when stepping into a new role is M. Watkins, "The First 90 Days", which is very helpful in formalizing an effective approach to succeeding quickly when in a new management role.
It is worth trying to get some education in people management. While much of it is common-sense, it's worthwhile covering the basics -- the applicable laws, managing conflicts, that sort of thing. I have yet to find a good, practical book on organizational engineering (if anyone has a suggestion, please post it), but this is an area that I feel someone in your role should seek to understand well, because it has a big impact on the success of a business.
One of the most important, fundamental skills for a senior level manager is understanding finance. I recommend B. Knight, "Financial Intelligence" as a primer.
My favorite book on business strategy is M. Porter "Competitive Strategy", however, this book and all other business strategy books should be taken with a large grain of salt. They often suffer from survivorship bias, being applicable only to certain industries and times, and in at least one famous case, allegedly faking the data used to draw their conclusions. I treat business strategy books as leisure reading that simply provides another perspective.