Real Version of Calculus of Complex Variable (II): Cauchy's Point of   View
  As was the case in a previous paper, the differential form x+ydxdy plays the role that the variable z plays in the standard calculus of complex variable. The role of holomorphic functions will now be played by strict harmonic differential forms in the Kaehler algebra of the real plane. These differential forms satisfy the Cauchy-Riemann relations. No new concept of differentiation is needed, and yet this approach parallels standard Cauchy theory, but more simply. The power series and theorem of residues belong here at the end, unlike in the previous paper. 
Jose G. Vargas
math.GM