When collecting revenue stamps, acquiring decent reference material can be quite a challenge. Catalogues which cover one country or groups of countries (such as Barefoot's
United Kingdom Revenues,
British Commonwealth Revenues,
Benelux Revenues etc) exist, but these are sometimes hard to find especially if they are out of print.
Until the early 20th century, there were catalogues of worldwide revenues, most notably Forbin, whose latest edition from 1915 is luckily freely available online:
***Link Removed***Hypothetically, would it be possible to produce an up-to-date catalogue of worldwide revenues? This could either be a traditional printed catalogue, maybe something along the lines of Stanley Gibbons'
Stamps of the World for postage stamps, or something online like
Stampworld.
The challenge is obviously the sheer scale - there are many thousands of revenue stamps out there, and it is difficult to obtain information about certain countries - but do you think such a catalogue would ever actually be possible?