This is a backed handaxe (15 cm long) from Remi sur Creuse /France, dated most probably to OIS9. On the pictures you can recognize that a straight back (the passive part of the instrument) is formed by remains of the original cortex of an elongated flint cobble and by some rough retouches. The contralateral active part of the bifaces is formed a sharp and straight edge. The point shows traces of later curation by a “tranchet blow” (not infrequent during the Acheulian of France, especially in the Somme region). The two sides of the handaxe show very different patination by postdepositional processes.
Backing on bifacial tools is a technique, known and studied mainly from the Middle European Micoquian (Keimessergruppe: KMG) in Germany, Poland and Moravia. Such inventories are mainly dated to OIS5, (4) and 3.
In Poland there are even several older sites with clear Micoquian annotations assigned to OIS6- OIS 8. At the important Biśnik Cave , excavations have revealed a more or less complete depositional sequence covering the period of MIS 8 to the Holocene. Micoquian backed artifacts appear within the long sequence during OIS8, 7, 6, 5e, 5d and 3. During OIS 6, the Micoquian is the best known unit of the early phase of the Middle Palaeolithic in southern Poland. The most abundant inventory was discovered at the site of Pietraszyn 49, which was dated by radiometry to OIS 6 (ca 160 k.a. BP). Pietraszyn 49 already shows he whole spectrum of bifacially retouched Micoquien tools. In N/W Europe first typical “Keilmesser” can be found at Mesvin IV (Belgium; U/Th dates: 250-300 k.a). Other sites with a KMG-like inventory are also known in this region. (http://www.aggsbach.de/2012/05/keilmesser/).
While backing was an integral of the “Micoquian”, the technique per se was also used in other early technocomplexes. In addition, it has to be mentioned that medium and large sized backed handaxes are rather rare in ensembles of the Middle European Micoquian, while true bifacial knifes are common.
In W-Europe backed Handaxes like the handaxe from Remi sur Creuse shown here, were a functional equivalent to “Keilmesser” but are not part of a “Micoquian tradition” and are attested in Acheulian ensembles since OIS13. Backing is not confined to the Micoquian and Acheulian of Europe but is also known from Middle Pleistocene Acheulian and Yabroudian Handaxes of Israel, Syria, Egypt and the Maghreb.
Producing the backed handaxe from Remi sur Creuse began with the choice of a suitable flint pebble of considerable length. Backing occurred early during the knapping process and not by chance. A contralateral straight edge was intentionally created. The artifact was used and later curated when the point was damaged. The hominid, who made this artifact had a clear geometrical and practical conception in mind, when he decided to make it some 300-400 k.a. ago.
Sorry no papers about the theme in the net but you should notice the excavations at the Biśnik Cave:
THE BIŚNIK CAVE IN SOUTHERN POLAND:RECONSTRUCTION OFTHE PALAEOLITHIC CAVE HABITATIONIN RELATION TO THE ENVIRONMENTAL CHANGES (free pdf)