Hey fellow rugger. I too play university rugby, and have found my speed increasing as well as endurance. How you ask? By changing my training and how I do it. I don't have a bunch of articles for you, but I can give you a recipe that should give you some of the success I have been finding...
1) Do hang snatches and power cleans. Do them. Once a week each. If you don't know the form, learn it.
2) Be more exploseive overall in your training. With say, a bench press, lower it slowly and explode fast as possible to the ceiling. Not all one speed. When doing sprints, focus on your
first three steps. I like 10 meter sprints jogging in between, while zigzagging across the field (that is the type of random speed you need in rugby). Also, make sure to do backpeddling
(running backward) training.
3) Eat several times a day, not Wendy's once a day. This is proven to sustain you as a lean machine. To hell with low carb and all that shit-just eat good food often.
4) Combine squats and lunges, I can feel the running power this cocktail has given me.
5) Abdominals and lower back are so important for running. Murder them when you train, or you will feel murdered on the field.
6) Last, try these sprints: sprint a quarter of the field, drop and lay down w/your head pointing the direction you are running. Wait 5-10 seconds, jump up, turn around and sprint to midfield (focusing on those first few steps of course) and repeat. You can have someone use a whistle if you like. These are pretty much hell and you may puke, but they will help you
reach your goals. P.S. Do all your running on grass with cleats on. Period.
Hope I could help, and let me know how this insanity works out for you. --JC