See the link bellow.
Again, H & k is cited in one of the most important magazine specialized in Discus fish, pictures attached.
H & K is, in a report, the German magazine, Discus live, by Bernd Degen.
H & K is in a story book Discus Book 02, the Aquapress, by Heiko Bleher see photos.
Report in an electronic journal publishes the work of H & K.