a^{c0}_{a0} b^{a1,v1}_{c1,v0} c^{c1}_{a2} eta1^{a2}_{a1} a+(a0) a+(v0) a-(v1) a-(c0)
+a^{c0}_{a1} b^{a2,v1}_{c1,v0} c^{c1}_{a0} gamma1^{a1}_{a2} a+(a0) a+(v0) a-(v1) a-(c0)