Looking for a reference on the observation that the set of stable matchings form a distributive lattice. This is attributed to Conway by Knuth in "Marriages Stables" but I would like an explicit reference if possible, likely a text book. An undergrad student needs it for his bibliography in a term paper.

strong text Conway discovered it when visiting Montreal contemporaneously to Knuth's lectures on the marriage problem. These lectures are in print, published by Centre de Recherche Math of Universite de Montreal. 

