This article was published about a quarter of a century ago. Now it is available on the Web, on a site of Oberösterreichisches Landesmuseum:
• Josef Reichholf, 1988 – Der Schlangenadler Circaetus gallicus in Bayern: Ein seltener aber regelmäßiger Durchzügler am Alpennordrand [The Short-toed Eagle in Bavaria: A Rare but Regular Migrant Along the Northern Fringe of the Alps] // Anzeiger der Ornithologische Gesellschaft in Bayern, 27 (1): 115-124. – 
(De) /map/.
These old short texts have been found recently on the Net:
• Bas van Balen, A. R. Compost, 1989 – Overlooked evidence of the Short-toed Eagle Circaetus gallicus on Java // Kukila. Vol. 4 – No 1-2 – P. 44-46. – (En) /map/;
• Wolfgang Rowold & Harald Weidener, 1999 – Beobachtung eines Schlangenadlers (Circaetus gallicus (Gmel.,1788)) in Marienmünster, Krs. Höxter [Observation of the Short-toed Eagle in Marienmünster] // Egge-Weser. Bd. 12. – S. 61. – (De) /map/.
And a work on flight properties of Palearctic Eagles, where Short-toed Eagle is one of the research objects:
• Kirmse W., 1998 – Morphometric features characterizing Flight Properties of Palearctic Eagles // Holarctic Birds of Prey. – P. 339-348. – (En).
Three more more articles are found on the Net:
• Marc Förschler, 2000 – Übersommerung eines Schlangenadlers (Circaetus gallicus) im Nordschwarzwald 1999 [Summering Short-toed Eagle (Circaetus gallicus) in the Northern Black Forest] // Naturschutz südl. Oberrhein 3: 69-73. – (De) /map/ (source – the Fachschaft für Ornithologie Südlicher Oberrhein (FOSOR) website).
• Matthieu BERNARD, 2003 – Observation en Auvergne d’un Circaète Jean-le-Blanc (Circaetus gallicus) bagué [Observation of ringed Short-toed Eagle (Circaetus gallicus) in Auvergne] // Le Grand Duc 62: 47. – (Fr).
Also other mentions of Short-toed Eagle can easy be found on the LPO Auvergne website including a work of Bernard Joubert on Haute-Loire /map/:
• Bernard JOUBERT, 2003 – Le Circaète Jean-le-Blanc (Circaetus gallicus) en Haute-Loire: données statistiques sur la reproduction dans la région de Langeac (Haut-Allier) [Short-toed Eagle (Circaetus gallicus) in Haute-Loire: statistical data on the reproduction in the region of Langeac (Haut-Allier)] // Le Grand Duc 63: 1-6. – (Fr).