The excavations of the pyramid of Sahure

The excavations of the Sahure pyramid are closely connected with the German archeolog Ludwig Borchardt, who has excavated the whole complex of Sahure between 1907-1908. These excavations are described in German in the remarkable book

Ludwig Borchardt, Das Grabdenkmal des Königs S'a3ḥu-Rec,
Band 1: Der Bau, J.C. Hinrichs, Leipzig, 1910,
Band 2: Die Wandbilder, J.C. Hinrichs, Leipzig, 1913

It can be downloaded from the Uni Heidelberg
Here is how it looked after the excavations made by Borchardt between 1902 and 1908 (picture from Borchardt 1910 p.6).