Across the space frontier / by Joseph Kaplan ... [et al.] ; ed. by Chesley Bonestell ; ill. by Chesley Bonestell, Fred Freeman, Rolf Klep Balkans : frontier of two worlds / by William B. King and Frank O'Brien Bulgaren in ihren historischen, ethnographischen und politischen Grenzen, (679-1917) : (Atlas mit 40 Landkarten) = The Bulgarians in their historical, ethnographical and political frontiers = … Verdun to the Vosges : impressions of the war on the fortress frontier of France / G. Campbell true facts about the disputed frontiers of Europe / by M. Vibart Dixon Alaska : the last frontier / H.W. Clark Rapport de la Commission de Démarcation de la Frontière Germano-Néerlandaise = Report by the Demarcation Commission of the Netherlands-German Frontier Passing it on : short talks on tribal fighting on the North-West frontier of India / Andrew Skeen ; wih a forew. by Philip W. … Among Boers and Basutos and with Barkly's horse : the story of our life on the frontier (extended and throughly revised to date) / F.A. … Campaigns on the North-West frontier / by Captain H.L. Nevill Proeve van beschouwingen over de verdediging van een belangrijk deel van Nederlands grondgebied : Het oostelijk frontier / L. Frankamp Frontier warfare and bush fighting