Spring Flowering Bulbs: on this web page, look for "Spring Flowering Bulbs, G1742". It has excellent information on the selection and care of spring-flowering bulbs, from the Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln Bulb.Com: very comprehensive information on flowering bulbs in general, from The Netherlands Flower Bulb Information Center, and the International Flower Bulb Center Growing Hardy Bulbs: basic information on bulbs, and descriptions of the most common spring-flowering bulbs; Horticulture and Crop Science, Ohio State University Extension Fact Sheet
Information on Daffodils: very comprehensive information on daffodils (Narcissi); Department of Horticulture, University of Missouri, Columbia, Missouri, USA American Daffodil Society: official web site of the American Daffodil Society; excellent information on daffodils and links to daffodil bulb sources