Need Help 5 X 7 Glass Plate Film Holder

[irismate]

Hi, I need help.
I inherited my grandfather's photographic material.
Among this material is a 5 X 7 Glass or Paper Plate Film Holder that I don't know at what camera(s) belongs or in what brand and models can be used.
So I kindly ask if anyone can help me in its identification. Pictures:
http://imageshack.com/a/img196/774/fafy.jpg
http://imageshack.com/a/img703/951/yu28.jpg
http://imageshack.com/a/img198/5630/op5g.jpg

Frame Measures:
18 cm = 7"
13,1 cm = 5,1 "
Exterior Measures:
20,5 cm = 7.87"
14,1 cm = 5,51"
thickness: 1,9 cm
slot thickness: 0,6 cm

Thanks.

[Cheffalo]

They remind me of the glass plate holders for my quite slender Reisekamera, Kleffel & Sohn, Berlin: http://www.flickr.com/photos/cheffalo/8563731980/in/set-72157627148282242
I'm really not an expert but from what I've seen these kind of holders goes for the more rectangular cameras, rather than the more square ones. I'm looking forward to someone more knowledgeable to answer this.