found: Studio F.M.B. San Marino, pianta della repubblica, centri storici, 1982:map recto (Serravalle)
found: BGN, 9-30-83(Serravalle, PPL, 43°57ʹN 12°30ʹE)
found: Wikipedia, July 25, 2017(Serravalle (San Marino); a castello located in the European republic of San Marino; the most densely populated municipality in San Marino; in medieval times this town was called Castrum Olnani (later Olnano); Serravalle attached to San Marino in 1463, during the last territorial expansion of the Republic; 43°58ʹ9.98ʺN 12°28ʹ42.12ʺE)