BioStor
 | The genera of Hydrophyllaceae and Polemoniaceae in the southeastern United States K A Wilson (1960) Journal of the Arnold Arboretum 41: 197-212 |
 | A REVISION OF THE PHACELIA CRENULATAE GROUP HYDROPHYLLACEAE FOR NORTH AMERICA N D Atwood (1975) Great Basin Naturalist 35: 127-190 |