There are several offline resources available worldwide.

United Kingdom

edit
Wikimedia UK

Wikimedia UK has several World War One related reference books, and funds to purchase more if required. At present, it has:

  • Smyth, W.H. (2009). The Sailor's Word-Book: A Dictionary of 14,000 Nautical Terms. England: Anova Books, UK. ISBN 9780851779720.

Wikimedia UK is planning to purchase, for general use by editors:

  • Beckett, Ian F. W. (2002). The First World War: The Essential Guide to Sources in the UK National Archives (1. publ. ed.). Richmond: Public Record Office. ISBN 9781903365410.