Using elements in the form of arbitrary sectors, the author has devised a plan for solving plane problems of elasticity by the force method. The method is characterized by a smaller number of nodes, a more convenient computation and a perfect adaptability to the particular shape of the region in question.
Pian, T.H. H.and Tong, P.,Basis of Finite Element Methods for Solid Continua, International Journal for Numerical Methods in Engineering,1,1,(1969),3-28.