1952 - February or mid ? source(s) ?

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@Mark83: (who started the article in 2004)

The fourth sentence of the introduction says Construction began in mid-1952. The info-box says 'February 1952' ... what's right ? Does anyone have a source ? --Neun-x (talk) 14:08, 30 September 2018 (UTC)Reply

@Neun-x:. I'll have to dig for a reference. Leave it with me Mark83 (talk) 18:34, 28 December 2018 (UTC)Reply