Archean
McLennan, S. M., Taylor, S. R.. and 
     McGregor, V. R., 1984, Geochemistry 
     of Archean metasedimentary rocks
     from West Greenland:  Geochimica
     et Cosmochimica Acta, v.  48, 
     p. 1-13.

Early Proterozoic
Loukola-Rustkeeniemi, K. and 
     Heino, H., 1996, Geochemistry and
     Genesis of the Black Shale-Hosted
     Ni-Cu-Zn Deposit at Talvivaara, Fin-
     land:  Economic Geology, v. 91,
     p. 80-110.

Late Proterozoic
Loukola-Rustkeeniemi, K. , Kuronen, U. 
     and Arkimaa, H., 1997, Geochemical com-
     parison of the metamorphosed black
     shales associated with the Vihanti Zinc
     deposit and prospects in Western Fin-
     land:  Geological Society of Finland
     Special Paper 23, p. 5-13.

Ordovician-Northern Appalachia
Fyffe, L. R. and Pickerill, R. K., 1993,
    Geochemistry of Upper Cambrian-Lower 
    Ordovician black shale along a north-
    eastern Applachian transect:  Geological
    Society of America Bulletin, v. 105, 
    p. 897-910.

Silurian-Maine and Central Europe
Cullers, R. L., Bock, B., Guidotti, C. V., 1997,  
     Elemental distributions and  neodymiun 
     isotopic compositions of Silurian meta-
     sediments, western  Maine, USA:  Re-
     distribution of the rare earth elements:  
     Geochimica  et Cosmochimica Acta, v. 61,
      p. 1847-1861.
Storch, P. and Pasava, J., 1989.
     Stratigraphy, chemistry and origin of
      the Lower Silurian black graptolitic
      shales of the Prague Basin (Barrand-
      ian, Bohemia):  Vestnik Ustredniho ustavu 
      geologikeho, v. 64, p. 143-162.

AVERAGE SHALE
Drever, J. T., Li, Y.-H., and Maynard, J. B., 
     1988, Geochemical Cycles:  the  contin-
     ental crust and the oceans,  in Chemical 
     Cycles, Gregor, C. B., Garrels, R. M. , 
      Mackenzie, F. T.,  and Maynard, J. B. 
      (eds.), New  York, John Wiley, p. 17-53.