NOte: this was written to help a friend find a special series document on winter fighting, but you can adapt the technique to find a lot of other stuff...
www.ahco.army.mil/site/index.jsp
Linka to main site
Hit the digital Documents tab at the top of the page, then hit the search button.
Doing a search for "Special Series" on the search function brings up the following.
-Page 1 of results-
German Coastal Defenses ( Special Series No. 15 )
German Military Training ( Special Series No. 3 )
The Development of German Defensive Tactics in Cyrenaica - 1941 ( Special Series No. 5 )
Japanese Mortars and Grenade Dischargers ( Special Series No. 30 )
Japanese Parachute Troops ( Special Series No. 32 )
German Military Abbreviations ( Special Series No. 12 )
Index to Intelligence Publications ( Special Series No. 23 )
The German Motorized Infantry Regiment ( Special Series No. 4 )
German Infantry Weapons ( Special Series No. 14 )
German Antiaircraft Artillery ( Special Series No. 10 )
Japanese Tank and Antitank Warfare ( Special Series No. 34 )
The German Armored Army ( Special Series No. 2 )
British Commandos ( Special Series No. 1 )
Guide to Maps of the Far East ( Special Series No. 31 )
Japanese Field Artillery ( Special Series No. 25 )
Morale-Building Activities in Foreign Armies ( Special Series No. 11 )
British Military Terminology ( Special Series No. 13 )
Artillery in the Desert ( Special Series No. 6 )
Company Officer's Handbook of the German Army ( Special Series No. 22 )
Japanese Tanks and Tank Tactics ( Special Series No. 26 )
Enemy Air-Borne Forces ( Special Series No. 7 )
German Doctrine of the Stabilized Front ( Special Series No. 17 )
Soldier's Guide to the Japanese Army ( Special Series No. 27 )
Japanese Infantry Weapons ( Special Series No. 19 )
German Mountain Warfare ( Special Series No. 21 )
-Page 2 of results-
German Ski Training and Tactics ( Special Series No. 20 )
German Winter Warfare ( Special Series No. 18 )
German Tactical Doctrine ( Special Series, No. 8 )
The German Squad in Combat ( Special Series, No. 9 )
Japanese Defense Against Amphibious Operations ( Special Series No. 29 )
Click on the "German Ski Training and Tactics" hyperlink.
Should bring up a page like this
Click on the icon the pointy arrow is pointing at, and wait...wait...
Don't worry. The program's working. It hasn't locked up. Just wait about 5-10 minutes (on broadband, lol); until eventually the PDF appears in the popup window which appeared when you clicked on that icon.
Then click on the button I'm pointing towards to save it to your hard drive.