See also this post on the old Falke forum.
These catalogues from the distributor Fern-Kauf-Nord are undated but appear to be from the mid-to-late 1950s. They have the same cover, but one includes airguns by Falke and the other by Weihrauch.
Like the Burgsmüller (Burgo) company, FKN adopted the unfortunate practice of renaming all the airgun models, thus obscuring their origins, apart from ones that are clearly identifiable, such as the BSFs, Falkes etc
See also gallery entries for 'Burgo' and 'AKAH'
Unfortunately there is no date printed on either catalogue, unless I'm missing it. I estimated a rather vague "mid-to-late 1950s" because most of the guns I'm familiar with were definitely on the market by then.
My best guess is 1959, for two reasons.
One is that the edition with Weihrauchs in it appears to include the HW35E, which we know was in circulation by 1959.
The second reason is that the two editions pictured seem to date from the same year, and share the same cover photo. But one brochure features Falke airguns and the other does not. We know that Falke stopped producing guns in 1959 after its MD and founder had a heart attack. This could be the reason the Falke range was abruptly pulled from the catalogue and a deal done with the Weihrauch factory to fill the gap.