Fig. 3
From: A generalized framework for the collinear restricted four-body problem with a central dominant mass

Representation of Libration points locations (rubin red dots) derived from intersections of iso-contours curves Θx(x, y) = 0 (in green) and Θy(x, y) = 0 (in grey) in the concentric restricted four body problem where μ0 = 0.75 and μ = 0.1