+// 13
+// N5+-----+-----+N6 +-----+-----+
+// /| /| /| /|
+// 12+ | 14+ | + | +25 + |
+// / | / | / | / |
+// N4+-----+-----+N7 | QUADRATIC +-----+-----+ | Central nodes
+// | | 15 | | HEXAHEDRON | | | | of tri-quadratic
+// | | | | | | | | HEXAHEDRON
+// | 17+ | +18 | + 22+ | +
+// | | | | |21 | | |
+// | | | | | + | 26+ | + |
+// | | | | | | |23 |
+// 16+ | +19 | + | +24 + |
+// | | | | | | | |
+// | | 9 | | | | | |
+// | N1+-----+-|---+N2 | +-----+-|---+
+// | / | / | / | /
+// | +8 | +10 | + 20+ | +
+// |/ |/ |/ |/
+// N0+-----+-----+N3 +-----+-----+
+// 11