In her 21 November (4 December NS) 1914 letter to Nicholas Alexandra mentions Warsaw being bombed and the hospital train of their son stuck in the city while this is going on
Alfred Know in his book "With the Russian Army 1914-1917" (see archive.org) Volume I page 198 has "German aeroplanes throw bombs daily on Warsaw" 5 December 1914 NS
the German 9th Army was outside Warsaw at this time and 20 November 1914 had the following FFA 30,4,25,17,15