Paolo Romani (IZ1MLL) has recently released version 5.3 of his SDRSharp PDF Guide. The book is available for download on the Airspy downloads page, just scroll down to the title "SDR# Big Book" and choose your language.
As before the document is a detailed guide about how to use SDRSharp (SDR#), which is the software provided by Airspy. While intended for Airspy devices, SDRSharp also supports a number of third party SDRs, including the RTL-SDR, and it is the software we recommend starting with when using an RTL-SDR.
Youssef Touil hasn't rested for a moment and the SDR# releases have been moving forward in leaps and bounds with new Denoisers (NINR), CCC, Audio/Baseband records and the new menu features.
I also had to re-update my Big Book PDF to v5.3 as a result!!
I have also implemented the SpyServer section a lot in multi OS and a chapter "Ideas and Suggestions" with two paragraphs: SDR & MacOS and the other using SDR# with two multiple monitors.