Here's a few:
"A PVRC Monograph of the 1949 Classic" "Development of General Formulas for Bolted Flanges" by Waters, Rossheim, Westrom & Williams. It has the derivation of all those flange factors.
Taylor Forge Bulletin #45 "Design of Flanges for Full Face Gaskets." Has the "Modified Rossheim Method" for full-face gaskets
A.E. Blach, "Bolted Flange Connections for Non-Circular Pressure Vessels" ASME PVP-158, 1989. pp. 97-104.
Cook & Guerreri, "Deflection in Gasketed Joints, Machine Design{I think}, March 14, 1968, pp.149-50.
R. Swick, "How much pressure will that Gasket Take?" Machine Design Nov. 24,1977
WRC #314 "Bolted Flange Connections with Full Face Gaskets," by Blach, Bazergui & Baldur, May 1986.
Also check out the Dutch Stoomwesen, BS5500, etc. flange analysis methods - a little bit different than ASME App. 2