It is such a great book to get you in the right mindset and prioritize your days to help you achieve your long term goals. 

One thing you might ask yourself is what goals are you looking to achieve?  

They are avid readers so I want to send him a couple books that can help them achieve their goals.

This is important for the first handful of flips or rental. 

https://www.biggerpockets.com/forums/12/topics/386159-whats-the-1-percent-ruleIn this case, aim for achievable monthly rent of 1% of total development cost, not acquisition cost ("purchase price").

Can't speak for the others from first hand research.Rules vary in terms of the threshold for eligibility, eg: >2 or >3 units, rate of growth allowed each year, rate at which capital expenditures can be translated into increases.

I have seen how networking works first hand. 

You are in the right place for the knowledge needed to achieve your goals.

You get the property for a small fee up front, can still achieve cash flow, any improvements benefit you directly, you don’t tie up one of your traditional mortgages.

It’s simply an achievement that gives you more options to help buyers and sellers, allows you to pull better data and info on properties, and saves you money by giving you the ability to showcase and market your own homes on the MLS.