I am 31 (female) and have been running for about 4 years now although the real intensity was came in the past two years, my pb in marathon is 3hrs 8 min, in half 1.32, 70 min for 10 miles and 42 min for 10ks. It is clear that I need to get some speed going if I want to break three hours this year or get even further. Can anyone recommend a training schedule, a book, articles that could give me guidance on how to get faster?