1/2 a^{a0,a1}_{v0} b^{}_{a2,a3} eta1^{a3}_{a1} eta1^{a2}_{a0} a+(v0)
+1/4 a^{a0,a1}_{v0} b^{}_{a2,a3} lambda2^{a2,a3}_{a0,a1} a+(v0)
+a^{a0,a2}_{v0} b^{}_{a1,a3} eta1^{a3}_{a2} a+(a1) a+(v0) a-(a0)