Resources (images, documents, journals, etc.) come from a variety of sources. They can be consulted by partner institutions or explored as a whole. But they are mainly organised in collections. A collection is a selection of resources coming from one or several sets (institutional, private and other sources) but can also be made up of several chapters of a book for example. The particularity of the collections published by Problemata is their editorialization. This is done by research line or by autonomous constitution (e.g. for a collection of journal texts or an entire journal).