diff --git a/magloop.html b/magloop.html
index af3b87d..095f0af 100644
--- a/magloop.html
+++ b/magloop.html
@@ -323,6 +323,9 @@
                 
                 const a_coil_radius = loop_diameter_meters * 0.5;
                 const coil_length = cond_diameter_meters * spacing_ratio * loop_turns;
+                const N = loop_turns; 
+                const l = (N>1) ? (coil_length * 100.0) : (cond_diameter_meters * 100.0); // coil length in cm
+
                 var retval = 0.0;
                 
                 if(shape == "circle") {
@@ -334,33 +337,30 @@
                     }
                 } else
                 if(shape == "octagon") {
-                    const N = loop_turns; 
                     const s = (100.0 * loop_diameter_meters) * 0.414213; // side length in cm
-                    const l = (N>1) ? (coil_length * 100.0) : (cond_diameter_meters * 100.0); // coil length in cm
-                    const bOn2r = l / (1.09868411*s);
-                    //retval = 1e-6 * 0.016 * (N**2) * s * ( Math.log((2.613*s*N)/((N+1)*l)) + 0.75143 + ((0.07153*(N+1)*l) / (s*N)));
-                    retval = 1e-6 * 0.016 * (N**2) * s * ( Math.log(1.0/bOn2r) + 0.75143 + 0.18693*bOn2r + 0.11969*bOn2r**2 - 0.08234*bOn2r**4);
+                    const bOn2r = l / (1.306563*s);
+                    //retval = 1e-6 * 0.016 * (N**2) * s * ( Math.log((2.613*s*N)/((N+1)*l)) + 0.75143 + ((0.07153*(N+1)*l) / (s*N)));  // ARRL Antennas Book 17th Ed
+                    retval = 1e-6 * 0.016 * (N**2) * s * ( Math.log(1.0/bOn2r) + 0.75143 + 0.18693*bOn2r + 0.11969*bOn2r**2 - 0.08234*bOn2r**4); // F W Grover p753
+                    //retval = 1e-6 * 0.016 * (N**2) * s * ( Math.log(s/l) + 1.711976 + 0.075143*(l/s) + 0.017528*(l/s)**2 - 0.001766*(l/s)**4);
                 } else
                 if(shape == "hexagon") {
-                    const N = loop_turns; 
                     const s = (100.0 * loop_diameter_meters) * 0.57735; // side length in cm
-                    const l = (N>1) ? (coil_length * 100.0) : (cond_diameter_meters * 100.0); // coil length in cm
                     const bOn2r = l / (loop_diameter_meters * 115.470);
-                    //retval = 1e-6 * 0.012 * (N**2) * s * ( Math.log((2.0*s*N)/((N+1)*l)) + 0.65533 + ((0.1348*(N+1)*l) / (s*N)));
-                    retval = 1e-6 * 0.012 * (N**2) * s * ( Math.log(1.0/bOn2r) + 0.65533 + 0.26960*bOn2r + 0.07736*bOn2r**2 - 0.05504*bOn2r**4);
+                    //retval = 1e-6 * 0.012 * (N**2) * s * ( Math.log((2.0*s*N)/((N+1)*l)) + 0.65533 + ((0.1348*(N+1)*l) / (s*N)));  // ARRL Antennas Book 17th Ed
+                    retval = 1e-6 * 0.012 * (N**2) * s * ( Math.log(1.0/bOn2r) + 0.65533 + 0.26960*bOn2r + 0.07736*bOn2r**2 - 0.05504*bOn2r**4); // F W Grover p753
                 } else
                 if(shape == "square") {
-                    const N = loop_turns; 
                     const s = (100.0 * loop_diameter_meters); // side length in cm
-                    const l = (N>1) ? (coil_length * 100.0) : (cond_diameter_meters * 100.0); // coil length in cm
                     const bOn2r = l / (loop_diameter_meters * 141.4214);
-                    //retval = 1e-6 * 0.008 * (N**2) * s * ( Math.log((1.4142*s*N)/((N+1)*l)) + 0.37942 + ((0.3333*(N+1)*l)/(s*N)));
-                    retval = 1e-6 * 0.008 * (N**2) * s * ( Math.log(1.0/bOn2r) + 0.37942 + 0.47140*bOn2r - 0.014298*bOn2r**2 - 0.02904*bOn2r**4);
+                    //retval = 1e-6 * 0.008 * (N**2) * s * ( Math.log((1.4142*s*N)/((N+1)*l)) + 0.37942 + ((0.3333*(N+1)*l)/(s*N)));  // ARRL Antennas Book 17th Ed
+                    retval = 1e-6 * 0.008 * (N**2) * s * ( Math.log(1.0/bOn2r) + 0.37942 + 0.47140*bOn2r - 0.014298*bOn2r**2 - 0.02904*bOn2r**4); // F W Grover p753
                 }
+
                 if(loop_mode == "parallel") {
                     // then N==2, so divide by 4 to go from serial to parallel inductance:
                     retval *= 0.25;
                 }
+                
                 return retval; // In Henries
             }