Davidse - 41953 - United States
Eggert - s.n. - United States
Lactuca canadensis
Turner - 15-131 - United States
Yatskievych - 89-184 - United States
Yatskievych - 90-230 - United States
Yatskievych - 91-140 - United States
Yatskievych - 93-265 - United States