Adalbert Freiherr von Lanna (1836-1909) of Prague

On a recent visit to Sotheby's I was shown a lovely leaf from a Book of Hours, with a small miniature depicting St Margaret, and a border with a cherub and centaur:

Donato and Ercole de Silva

When cataloguing the pre-1500 manuscripts of the College of Physicians of Philadelphia recently, I needed to identify the owner of an Italian ink-stamp, in a copy of Macer, De virtutibus herbarum, in the form of a seal with the legend "COMES DONATUS SILUA":

and so I was pleased to discover that two of the standard reference books are available online:

"What Counts as Provenance Evidence?"

There is a detailed analysis of a variety of marks found in a single book here:
https://msuprovenance.wordpress.com/2013/10/08/problems-in-provenance-research/
under the title "What Counts as Provenance Evidence?", on the blog of the Special Collections Department of Michigan State University. It's worth a read. The following is an extract:

[...]

Some markings are relatively straightforward and easy to understand, while others are more mysterious. How many different marks do you see?  Let’s be literal at this stage and refrain from judgment about which particular inscriptions are important for determining provenance.  I count at least 15 different potential provenance markers on these two pages alone.  I’ll highlight those below:

Click to enlarge

[...]

Fritz Hasselmann (d.1894)

In my first blog-post two years ago I described the mark of Fritz Hasselmann, as found on several items at the Chester Beatty Library, Dublin.

Since then Lugt's Marques has gone online, so we now have far more information about Hasselmann, the sales of his collections, and a photographic example of his ink-stamp. Here are two more examples, one with the end of my thumb, as a guide to its scale:

The online Lugt entry for Ed. Schultze (also discussed in my old blog-post) has no new information, but includes a colour reproduction of his ink stamp. Another example online comes from the Cooper-Hewitt Museum.