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the Veteran Cycle Club of the UK is a good resource for Hercules information
https://v-cc.org.uk/
it is necesary to join to gain access to their archive of materials
they do have what is termed a "marque enthusiast" (M.E.) specifically for Hercules
there is an extensive holding of catalogues and brochures
unfortunately the years 1956-1957-1958 constitute a lacunae in their holdings
if you search online for information you will quickly discover that there is an unrelated Hercules marque based in Germany
if that be not eno' thar be a third Hercules cycle marque based upon the shores o' the subcontinent
there is an enthusiast Hercules site here you may have already discovered
https://herculesmuseum.wordpress.com/
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