How to Find 1945 Germany Maps and Meaning of Map References?

I'm trying to track down my late father's movemnts across Germany during April to May 1945 when he served in the 1st Battalion Royal Ulster Rifles. I have his service record and various useful references including this one:

Headquarters, 6th Airlanding Brigade

The maps mentioned are
1:250,000 DUSSELDORF Sheet K 52
1:250,000 OSNABRUCK Sheet K 53
HANNOVER 1:250,000 Sheet L53
1:100,000 M.5 SALZWEDEL
CENTRAL EUROPE 1:100,000 Sheet 65 LAUENBURG
1:100,000 Sheet K 6 ROSTOCK

Where can I find these maps to download? I'm OK with 6 digit map references assuing they are similar to OS grid refrences but what do references like these mean?

1 RUR at 0596 on main road to LENGERICH

PW taken by 1 RUR states that cross roads 3705 is held with two 88mm guns and two companies of infantry spread around houses

1 RUR entered BUER 4606

1 RUR have taken over LAHDE 8520


Thanks in anticipation.

 

This is a useful mosaic of all 1:100ks if you have a general area:
Europe A.M.S. / G.S.G.S. map 1:100,000 WWII

Lookup of many maps by series and online links if known:
New Resource - Topographic & Town/City Maps

 

Thanks - good find. I'd like to download the maps quoted so I can then stich them anda nnotate them in Photoshop.