Original sentence: Indeed, as Dr James McCardel pointed out in his "History of New Kilpatrick", captive bears do not live in dens, but in pits.It is approximately six miles (nine kilometres) from central Glasgow and is located on the site of the Roman Antonine Wall
Edited sentence: Indeed, as Dr James McCardel pointed out in his "History of New Kilpatrick" (the principal source for Bearsden's history), bears do not live in dens, but in pits.It is approximately six miles (nine kilometres) from central Glasgow and is located at  on the site of the Roman Antonine Wall