Polemonium caeruleum (Jacob's Ladder) .
"Handbook to the Severn Valley Railway Illustrative and Descriptive of Places along the Line from Worcester to Shrewsbury" by J. Randall
Polemonium, from its numerous leaflets arranged in pairs, has received the picturesque name of Jacob's ladder.
"Springtime and Other Essays" by Francis Darwin
Abscess-root (Polemonium Reptans L.) is another root with which serpentaria is often adulterated.
"Ginseng and Other Medicinal Plants" by A. R. (Arthur Robert) Harding
Phlox or Polemonium Family.
"The Wild Flowers of California: Their Names, Haunts, and Habits" by Mary Elizabeth Parsons