@article {532,
	title = {North American Flora. New York Botanical Garden},
	volume = {33},
	year = {1922},
	author = {Rydberg}
}
@article {533,
	title = {North American Flora. New York Botanical Garden},
	volume = {34(4)},
	year = {1927},
	author = {Rydberg}
}
