From the introduction:
Sources [for this compilation product] include Across the Board, Beasts in Velvet, Genevieve Undead, Paths of the Damned vol. 2: Spires of Altdorf, Paths of the Damned vol. 3: Forges of Nuln and White Dwarf.
Note the PDF is formatted "two-up" for booklet printing. The PDF has 14 pages; a printed and folded booklet would have 28 pages.