Donnell Clayton Donnell & Kaufmann J.E Kaufmann 
Modern European Military Fortifications, 1870-1950 [PDF ebook] 
A Selective Annotated Bibliography

This selected bibliography on modern European fortifications, from 1850 to 1950, provides a selection of the most important books and articles written on this topic. The work covers regions and countries and includes many sources on such popular topics such as the Maginot Line along with lesser known fortifications such as the Salpa Line and the Swiss National Redoubt. References for the fortifications that appear cover everything from the Iberian Peninsula to the Soviet Union and from Scandinavia to the Mediterranean countries.This work includes not only American and English, but also non-English publications. This source features books and articles done in the nineteenth and twentieth century ending in December 2000. Each contributor is a member of SITE O, an international fortifications research group. In addition to helpful annotations, each chapter includes summaries on the fortifications. Also features a multi-lingual glossary and reference maps.