Some key landmarks play their roles in narratives other than general histories of Philadelphia architecture, or even chapters of them. They may be found amid monographs tracing styles, building types, or other themes, which may be another place for us to identify Philadelphia-area buildings that should be mapped into our concordance.
Books that come to mind include Talbot Hamlin's Greek Revival in America, Richard Carrott's Egyptian Revival, Morrison's Early American Architecture, and other titles of this sort.
Similarly, Phoebe Stanton's book on early Gothic Revival churches or by Carroll Meeks on railroad stations include Philadelphia examples as key buildings.
On the other hand, biographical monographs on architects and geographically centered books tend to uncover often obscure buildings to discover detailed knowledge of their subject's perfomance or evolution, perhaps more detailed than this project would embrace in its broader sweep.
Guidebooks generally tend toward selective criteria that differ from those in the narrative constructions that we would choose to favor here.
Surveys like HABS would seem a natural resource, but these too often seem to map to other criteria, weighing early to colonial and early 19th-century examples, and often to imminent threats or geographically defined campaigns. Nonetheless, they will offer rich illustrative resources in the public domain in terms of photographs and, especially, plans for buildings nominated by their inclusion in other contexts. One may want to crop such plans for effectiveness as presented digitally, where the scale of the sheet can rarely be effective for both the detail and the whole simultaneously.
Vernacular examples present another challenge. Different monographs may well propse different examples to represent key types or points, and in that case we may have to seek to discern the key definitions of the type and choose to represent it without being swayed by the lack of repeated references affirming an individual building or being wedded to a particular example. But as yet there has been relatively litlle literature on distinctive local typer, and this may have to develop further in the future as that literature advances.
Illustration in architectural or popular journals commenting on architecture may be especially good representatives of period values, and may offer a sense closer to the period's than later retrospective scholarship has captured, especially where that favored the rarer instances of International Modernism over the buildings more frequently published and built in the period. The Avery Index may be a valuable tool in this respect; thus, a house published in the 1930s in the Architectural Record and American Architect and other journals may nominate itself for inclusion by virtue of representation there even where absent in almost all retrospective tellings.