Although this perspective has grown throughout Glen's prolific work and educational output the following seem particularly focussed here.
The Double Planetary activity and the Constellations
Energetic Activities
Energetic Plant Growth Dr Rudolf Steiner edited by Glen Atkinson (PhD)
Links to Glen's articles in which these things are discussed
Re: Links to Glen's articles in which these things are discussed
A particularly clear and fairly early statement of this approach can be found here with the process and inputs outlined.
"While giving the making process of the preparations, RS also outlined the basic effects of each preparation. He also gave some of the chemical processes that occur in each. In two cases, he indicated the influence a preparation has on the spiritual bodies. However, he did not extend this to all of them. As this is an important aspect of the overall thrust of this work, I have made an initial attempt at extending the interpretation of each preparation to include their spiritual activity. A summary follows:"
"While giving the making process of the preparations, RS also outlined the basic effects of each preparation. He also gave some of the chemical processes that occur in each. In two cases, he indicated the influence a preparation has on the spiritual bodies. However, he did not extend this to all of them. As this is an important aspect of the overall thrust of this work, I have made an initial attempt at extending the interpretation of each preparation to include their spiritual activity. A summary follows:"