Best education resource for buying apartment building

[Clayton Sneider]

Hey folks. I am interested in buying an apartment building. I have bought a couple of single family houses in the past as rentals, but I would like to learn more about buying either an apartment complex or possibly buying multiple single family units. Where is the best resource (preferably free) for learning about this? I can invest up to about $400K as a down payment. I would like to buy an asset that produces significant cash flow. I would prefer to buy something local to the Longmont CO area, but there are limited options, so I am open to out of state investing, but concerned about managing it. Thanks!