ERRATA SHEET 
e The following Equation (23) is to be substituted for the equation 
on page 28. 
= a,x tay tay tay + asx?y * aqxy? s a xy? 
X 2-442 2,52 4 x rm 
+5 | as x?ru^]) + a, UE + QU MX TU J 
+x | a,5(x2+42) * aix^ «y^p + a, ow] 
x 
ta + a — 
19 21 (5 
* 
= 2 2 2 2,42 
*gU taux ta, xiu a, xy* t a, X 
+4 [4,5 (x2-42) tax t a, ,Ix*-g*1] 
+y [estt + a, x^)? t a, Ix?