The Pennsylvania Shield Law provides an absolute privilege against compelled disclosure of confidential source information regardless of a party's "need for the information." Davis v. Glanton, 705 A.2d 879, 883 (Pa. Super. 1997). At a minimum, of course, the moving party may only seek materials that are reasonably calculated to lead to the discovery of admissible evidence. See Pa. R. Civ. P. 4003.1(a).