Equation Icon  2 ( 2 2 2 2) d-Δref k-- 4-ρa- 18ρ-a-- 0 = dη2 + 3 − λℓ2 − λ2ℓ2 Δref, (338a ) ( 2 2 2 ) ζref = 1-+ -3ρa---+ -9ρ-a--- Δref + 3Ha-dΔref. (338b ) 4 2λk2ℓ2 4λ2k2 ℓ2 4k dη