Per Axel Rydberg

Scandinavians Who Have Contributed to the Knowledge of the Flora of North America (Classic Reprint)

Catalogue of the Flora of Montana and the Yellowstone National Park (Classic Reprint)

North American Flora, Vol. 34: Carduales Carduaceae, Liabeae, Neurolaeneae, Senecioneae Pars (Classic Reprint)

A Monograph, North American Potentilleae (Classic Reprint)

Flora of the Black Hills of South Dakota (Classic Reprint)

Flora of the Rocky Mountains and Adjacent Plains

The North American Species of Physalis and Related Genera (Large Text Classic Reprint)

The North American Species of Physalis and Related Genera (Classic Reprint)

Carduales Carduaceae, Helenieae, And, Baeria, Lasthenia (Classic Reprint)

Flora of the Black Hills of South Dakota - Scholar's Choice Edition

Catalogue of the flora of Montana and the Yellowstone National Park

An Key to the Rocky Mountain Flora; Colorado, Utah, Wyoming, Idaho, Montana, Saskatchewan, Alberta, and Parts of Nebraska, South Dakota, North Dakota

Flora of the Black Hills of South Dakota - Primary Source Edition

Scandinavians Who Have Contributed to the Knowledge of the Flora of North America, Volume 1907, Part 1 - Primary Source Edition

A Report Upon the Grasses and Forage Plants of the Rocky Mountain Region, Volumes 1-10 - Primary Source Edition

Flora of the Rocky Mountains and Adjacent Plains, Colorado, Utah, Wyoming, Idaho, Montana, Saskatchewan, Alberta, and Neighboring Parts of Nebraska, South Dakota, and British Columbia

Scandinavians Who Have Contributed to the Knowledge of the Flora of North America Volume 6

Flora of Nebraska; Part 21, Rosales

Key to the Rocky Mountain Flora

Catalogue of the Flora of Montana and the Yellowstone National Park Volume 1

Studies on the Rocky Mountain Flora

Scandinavians Who Have Contributed to the Knowledge of the Flora of North America

Flora of the Sand Hills of Nebraska

A Report Upon the Grasses and Forage Plants of the Rocky Mountain Region, Volumes 1-10