I've had Gaffel and Reissdorf but if you can't find them here are the commercial examples as per the BJCP.
Available in Cologne only: PJ Früh, Hellers, Malzmühle, Paeffgen, Sion, Peters, Dom; import versions available in parts of North America: Reissdorf, Gaffel; Non-German versions: Eisenbahn Dourada, Goose Island Summertime, Alaska Summer Ale, Harpoon Summer Beer, New Holland Lucid, Saint Arnold Fancy Lawnmower, Capitol City Capitol Kölsch, Shiner Kölsch