Paper  bibtex   

@article{mahr2020a,
	title = {Working with batches of {PDF} files},
	volume = {9},
	copyright = {CC-BY 4.0},
	issn = {2397-2068},
	url = {https://programminghistorian.org/en/lessons/working-with-batches-of-pdf-files},
	language = {en},
	urldate = {2020-02-03},
	journal = {Programming Historian},
	author = {Mähr, Moritz},
	month = jan,
	year = {2020},
	note = {tex.ids: mahr2020c}
}