Here are some I would recommend (presuming you're looking to do buy and hold rentals):Personal Development: The Science of Getting Rich, Miracle Morning, The 7 Habits of Highly Effective People, Be Obsessed or Be AverageBusiness: The E-Myth, The Millionaire Fastlane, Good to Great, TractionReal Estate: The Millionaire Real Estate Investor, The Advanced Guide to Real Estate Investing,Finding and Funding Great Deals, The Book on Negotiating Real EstateI've also heard good things about How I Turned $1,000 into Five Million in Real Estate in My Spare Time and bought it but have yet to read it (as I'm not in rentals).

Often, the situation where the house is not habitable will trigger certain actions. 

Now you don't have to be good at every aspect you learn about, but it's vital in deciding where you want to go in this industry.

Strategic use of debt is vital, an automatic assumption that more is better in every circumstance is unwise, especially for those whose real estate investments coexist with other income, professional circumstances, retirement issues etc.We are in an unprecedented period of liquidity over the last 30-40 years.

Consider that some of her observations about the house may point to habitability issues that would need to be resolved by you.

Also, I've got a real estate browsing habit and I love houses.

@Ray Harrell : getting to 75 units is easy: start with 150 units in a F-class neighborhood, then wait a year.At the end of the year, you should have only 75 habitable units left!

If the Seller shows signs of having the same desire, they will give him the time to work it out.My main point is that communication with the existing lender is vital asap. 

I usually can get used from habitat or salvage yards.

. * [Not a habit you'd want to continue].Might going into a joint-venture with a developer (who'd build on the lots) help?