The full book contains several citations, here's one:
> The strongest evidence comes from D. M. Fanning ("Families in Flats", British Medical Journal, November 18, 1967, pp. 382-86). Fanning shows a direct correlation between incidence of mental disorder and the height of people's apartments. ... And it is not simply a case of people prone to mental illness choosing high-rise apartments.
> The strongest evidence comes from D. M. Fanning ("Families in Flats", British Medical Journal, November 18, 1967, pp. 382-86). Fanning shows a direct correlation between incidence of mental disorder and the height of people's apartments. ... And it is not simply a case of people prone to mental illness choosing high-rise apartments.
A Pattern Language was published in 1977.