For technical advice, articles, an extensive bibliography, web links and much more relating to the use of natural stone, visit:
resource
n. a supply or source of aid or support; something resorted to in time of need.

Armstrong, S. (2006) Lime. Church Building, Issue 101, Manchester.
Wright, G.A.A & Wheeler, W.A (1970) Masons' Marks on Wells Cathedral Church Friends of Wells Cathedral, Wells.