This is Pete Pfitzinger's training plan from his Advanced Marathoning book for mid-mileage marathoners who typically train less than 40 miles per week, but are willing to up their mileage to 55 miles per week during marathon preparation. This 18-week plan starts at 33 miles per week and peaks at 55 miles per week.
Be sure to buy his book if you don't already have it. It will provide a lot more details with regards to each workout.
This plan is being published with the permission of Pete Pfitzinger