For project background and methodology, see Cory James Young’s data article for an earlier iteration of this project hosted by Enslaved.org.
For a concise overview of the history of Pennsylvania slavery and abolition, see Doug Harper's Slave North Project.
For transcriptions of Pennsylvania's 1780 gradual abolition law in English and Spanish, see Yesenia Barragan's Free Womb Project.
For a detailed accounting of sources pertaining to Pennsylvania slavery, see George Nagle's AfroLumens Project.
For a database of slavery records from several northern states, including Pennsylvania, see the Northeast Slavery Records Index.