There are a few books out there on median lines.  There is one by Patrick Mikula that is "The Best Trendline Methods of Alan Andrews and Five New Trendline Techniques", that's not to bad..think its available on Amazon - but IMHO, he is just using the great Doctors work to sell his book.  Another by my mentor Timothy Morge, "Trading with Median LInes " is decent as well.  Lots of charts, but that's really the only way to learn about it.   The ones my by Dr. Dircea Dologa are too complex, as they are intermixing tons of other filters, and if you think median lines are confusing, just over lay his work...IMHO!!

For free resources, I would go to medianline.com and download the original free Action-Reaction course by Dr. Andrews.  It's a tough read.  A cleaner version exists on tradingnaked.com as well.  

Take Care Zen