Resources on Real Estate as Part of A Diversified Portfolio

[Paul Allen]

I am a financial planner. Took all the CFP courses and passed the test. Very (VERY) little of the course material focused on real estate as an investment. Stocks, bonds, and insurance products were covered in detail (don't get me started as to why), but not real estate.

I would like to find some resources that discuss the role of real estate in a diversified investment portfolio. Not resources that discuss exclusively real estate investing, but rather something that includes real estate in the portfolio next to the stocks, bonds, and annuities.

Thanks in advance!