Saartok T, Dahlberg E, Gustafsson JA (1984), Relative binding-affinity of anabolic–androgenic steroids—comparison of the binding to the androgen receptors in skeletal muscle and in prostate, as well as to sex hormone-binding globulin, Endocrinology 114: 2100–2106
Holterhus PM, Piefke S, Hiort O (2002), Anabolic steroids, testosterone-precursors and virilizing androgens induce distinct activation profiles of androgen responsive promoter constructs, J Steroid Biochem Mol Biol 82: 269–275
Potts GO, Arnold A, Beyler AL (1976), Dissociation of the androgenic and other hormonal activities from the protein anabolic effects of steroids. In: Kochakian CD (ed). Handbook of Experimental Pharmacology, vol. 43. Springer-Verlag: Berlin, pp 361–401.
British Journal of Pharmacology (2008) 154 502–521 on Steroid Pharmacology (great discussion)
Antonio J, Wilson JD, George FW (1999), Effects of castration and androgen treatment on androgen-receptor levels in rat skeletal muscles, J Appl Physiol 87: 2016–2019
If you are indeed interested, I can talk about these studies and what was so interesting about Anadrol specifically (co-regulators, hormone receptor complex, etc).
For example, Anadrol has a very weak binding affinity for the AR... in fact the Saartok study posted above determined that it was too low to even measure (interestingly Nandrolone was at the top when measured against methyltrienolone). Clearly biological activity is not correlating with the in vitro binding assays.
Or the Holterhus study discussing the hormone receptor complex and coregulators:
Results were due to specific ligand-induced conformation changes which determined how the hormone receptor complex can specifically interact with coregulators and neighbouring transcription factors. Meaning that the extent of activation depends on the structure of the response element (short sequence of DNA on the promoter that binds to the hormone receptor complex and regulates transcription).
This indicates that different shaped receptor complexes can fit differently. Coregulators may attach or not attach and behave much differently.
Can go more in-depth into why Anadrol has a different mechanism of action versus many other steroids... then we can discuss why it can be useful to implement it later in a cycle when the body starts to "fight" the growth signals.