As far as we now know, the number of joint ventures in the nineteenth century between publishers was small. Only 2% of the more than 1000 titles that made up the publisher's list of Gebr. Diederichs in the period 1828-1865 consisted of joint publications. The list books of the Erven F. Bohn for the entire nineteenth century only mention about 15 instances of co-operation (total list circa 1200 titles), and the list of more than 1400 titles of A.W. Sijthoff for the period from 1851-1886 only contains 31 joint productions, among which 16 publications together with Frederik Muller of Amsterdam and J.H. de Lange of Deventer for the Maatschappij tot Nut van 't Algemeen (Society for Public Welfare). Most co-operation schemes were once-only, long-term co-operation occurring only for long-running series, expensive reference works, dictionaries and international enterprises.
For enterprises involving large amounts of capital, publishers sometimes chose a form of co-operation in which one of the partners acted towards the bookshops as the publisher and the names of the other partners were not mentioned in the imprint, although the partnership was occasionally mentioned on the title page. The print run was no longer divided among the partners, but the tasks of the production and distribution process were divided. An example of such a permanent partnership were the publishers and mutual friends A.W. Sijthoff, Martinus Nijhoff and D.A. Thieme. This co-operation was called 'het driemanschap' (the triumvirate) and, in the second half of the nineteenth century, they published a large number of editions and reprints of literary works, such as the Romantische werken (1867-1872) by Jacob van Lennep and expensive enterprises such as Van Dale's Woordenboeken (Dictionaries) and the first seventeen parts of the Woordenboek der Nederlandsche Taal (Dictionary of the Dutch Language). In the latter production, they also divided the work: the paper and the printing, the retailing abroad, the sales in the Netherlands, the main administration and the shipping. A division of work also took place for the publication of the Schoolbibliotheek (School library) series (1871-1875) where the publishers Sijthoff, D.A. Thieme and C.L. Brinkman spontaneously arrived at a co-operation when they were planning a similar publication in the same year. Sometimes publishers also co-operated in other fields. The publishers Gebr. Diederichs and C.G. Sulpke, for example, jointly bought at list auctions; they later published inexpensive reprints of some of these remainders.
Another motive for co-operation was the increase of sales outlet. Publishers who also wanted to sell their titles abroad sought contacts with foreign colleagues. This concerned works in the Dutch language, which could, for example, be sold in Belgium, original works, or translations about Dutch culture, language, literature, etc. Co-operation also took place in order to publish an edition in several languages.
In a contract between A.W. Sijthoff, the initiator, and J.P. van Dieren of Antwerp for a joint new edition of the works of Conscience, not only the period of joint copyright and the clauses concerning fees were laid down, but it was also stipulated that Sijthoff would undertake the sales in the Netherlands and Van Dieren those in Belgium. The six parts were published in 1867-1870 in a print-run of 8550 copies, 2250 for the account of Sijthoff and 5250 copies for the account of Van Dieren.
The publisher Gebr. Diederichs co-operated with, among others, their German colleague F.C.W. Vogel and the Librairie Belge in Brussels. The co-operation between the Erven F. Bohn and the German publisher Diesterweg in Frankfurt and the publisher G. Kolff & Co. in Batavia also illustrates the importance of co-operation with foreign colleagues in order to achieve a larger sales outlet.
