Research links you need to know agout: ZVDD - DDB Grünpeck shootout

Via Der Spiegel comes the announcement of the Deutsche Digitale Bibliothek, which looks like it aims to provide a comprehensive index of digitalized objects from German archives, museums, and libraries. But don't we already have something like that, at least for printed books, in the Zentrales Verzeichnis Digitalisierter Drucke? I have no idea if the DDB is already including ZVDD data. Let's see how the two compare on a search for "Grünpeck." There are several digital editions of some of Josef Grünpeck's works available, so he provides a reasonable test case of what we might expect from the DDB.

First, the raw numbers:
ZVDD: 47
DDB: 20

That isn't reassuring at first glance, but the ZVDB looks like it contains a lot of duplicates. Let's dig into the numbers a bit more.

Year	Title	ZVDD	DDB	Total known
1496	Cicero, Paradoxa stoicorum  (dedication)	1	1	1
1496	Tractatus de scorra	28	6	7
1503	Mentulagra	1	1	1
1507	Zeichenauslegung	2	2	2
1508	Speculum	8	4	4
1515	Ad principes	1	1	1
1522	Dialogus	1	1	1
1524	Endlicher Beschluss 1524	0	0	1
1532	Prognosticum	2	2	3
1721	Friedrich und Maximilian	1	1	1
Other
1550	Egenolff compilation	1	0
1620	Egenolff compilation	1	1
TOTAL		47	20	22

There are actually only a few cases where ZVDD and DDB differ. The ZVDD knows about a 1787 edition of the Tractatus de scorra that the DDB doesn't list, and the ZVDD also includes a short work attributed to Grünpeck in one of Egenolff's prophetic compilations that the DDB doesn't include. That's not a huge improvement, however, as there are several additional facsimiles of other Egenolff editions beyond the ones known to ZVDD and DDB. On the other hand, the ZVDD has 4 redundant records for one edition of Grünpeck's Speculum, and 21 redundant records for various editions of the Tractatus de scorra, so that's one advantage that the DDB has. Finally, there are two missing facsimiles, one of the Prognosticum of 1532, and another of Grünpeck's Endlicher Beschluss concerning the conjunctions of 1524. For those, you'll need to refer to the Hungarian Electronic Library.