I would like to support Hans-Karl's view. Foucart's editions (Iena, Prenzlow-Lubeck, La cavalerie..., Campagne de Pologne) are as source editions a value in itself, over the times. Additionally you might consider Lechartier's La manoeuvre de Pultusk and Davout's Opérations du 3e corps 1806 - 1807. I believe all of them are available in Gallica.

WRT to a balanced history, the semi-official (general staff) work Der Krieg von 1806 und 1807 by Lettow-Vorbeck seems to me sufficient, of course looking from the Prussian side, but processing Foucart and others in a very fair way. Even Höpfner's work - same title - from 1850 tried so, but is outdated now. Both can be found electronically as well.

Best regards, Thomas