"Forcing spring bulbs". Greenshare factsheets. University of Rhode Island Landscape horticulture program. Archived from the original on January 18, 2013. Retrieved 15 July 2013.
"Forcing spring bulbs". Greenshare factsheets. University of Rhode Island Landscape horticulture program. Archived from the original on January 18, 2013. Retrieved 15 July 2013.