And as the picture at that page shows, these are not a standard-shaped stamp (Rectangular with perforations) but shaped to look like a pile of album sleeves, with their corners at angles.
Fortunately the come pre-gummed to "peel'n'stick", so there is no need for them to be capable of forming a 'sheet' of attached stamps.
I've made a point of using them for the last week or so

CHEERS
Nigel