1/4 a^{a0,a1}_{v0,v1} b^{v2}_{a2} c^{a3}_{v2} gamma1^{a2}_{a3} a+(v0) a+(v1) a-(a1) a-(a0)
+1/2 a^{a0,a2}_{v0,v1} b^{v2}_{a3} c^{a1}_{v2} eta1^{a3}_{a2} a+(v0) a+(v1) a-(a1) a-(a0)