This type of learning material, lacking any desperate 'ELI5' oversimplifications and laying out the proper amount definitions and equations without having to resort to fancy animations to keep the -quite often indolent- reader engaged, is unfortunately scarce in today's web, as is evident from the website's layout.
Here are two favorite readings for anyone willing to delve more into the subject:
Orbital Mechanics for Engineering Students by Howard D. Curtis
Here are two favorite readings for anyone willing to delve more into the subject:
https://www.amazon.com/Orbital-Mechanics-Engineering-Student... https://www.amazon.com/Fundamentals-Astrodynamics-Second-Dov...Another great textbook as suggested by musgravepeter in the comments is
https://www.amazon.com/Fundamentals-Astrodynamics-Applicatio...