SHEEP
A package for symbolic mathematics, especially tensor analysis and General Relativity, developed by Inge Frick in Stockholm in the late 1970s to early 1980s. SHEEP was implemented in DEC-10 assembly language, then in several LISPs. The current version runs on Sun-3 and is based on Portable Standard LISP.
["Sheep, a Computer Algebra System for General Relativity", J.E.F. Skea et al in Proc First Brazilian School on Comp Alg, W. Roque et al eds, Oxford U Press 1993, v2].
http://riaca.win.tue.nl/archive/can/SystemsOverview/Special/Tensoranalysis/SHEEP/index.html.