I am trying to find papers that describe constant low-thrust spiral up-coast-spiral down phasing maneuvers for circular and non-circular orbits. The thrust is assumed to be fixed at $T_{const}$ when the engine is turned on and $0$ when the engine is turned off during the coast phase.

Circular Orbits

The related question Phasing maneuvers; methods to travel between satellites with very similar circular orbits contains an excellent answer that describes a low-thrust spiral up/down maneuver for a perfectly circular orbit.

Q1: Is there a reference to learn more about this method for low-thrust circular orbit phasing?

Non-circular Orbits

The closest I could find were these two papers:

• Analytic Orbital Averaging Technique for Computing Tangential-Thrust Trajectories by Gao and Kluever (2005)Analytic Orbital Averaging Technique for Computing Tangential-Thrust Trajectories by Gao and Kluever (2005)
• Small Satellite LEO Maneuvers with Low-Power Electric Propulsion by King, Walker, and Kluever (2008)

Q2: Is there a different reference that contains a simpler description of a spiral up-coast-spiral down maneuver that can be used for low-thrust non-circular phasing with $e \approx 0.2$ ?

I'm basically trying to find the papers that people in the industry refer to for low-thrust phasing in the preliminary design stage. Analytic methods are preferred. Any references and insights would be deeply appreciated!