Osteoblasts and Bone Formation
Molecular Biology of the Cell, 4th edition - searchable
Broken Bones - NHS health encyclopaedia
An Introduction to Bone Repair
http://www.youtube.com/watch?v=vcsPjThU-5Q&feature=related - Note that the doctor in this video correctly states that c.99% of the body's calcium is stored in bone, but that the accompanying on-screen text wrongly states the skeleton is 99% calcium!