Dahlia, bedding varieties is New York's Cornell University Cooperative Extension which covers palnt characteristic, how to grow it, and what varieties are available. 

 

Dahlia Culture is an Oregon State University Cooperative Extension publication which covers how to successfully cultivate this flower.

 

Dahlia, medium to tall varieties is a Cornell Unversity Extension publication which covers what varieties are available and how to cultivate it. 

 

Dahlia spp. Dahlia is a Florida Extension publication which has information on how to cultivate this crop.

 

 Dahlia x 'Figaro Improved' Figaro Improved Dahlia is a Florida Extension publication which covers all aspect of this cultivar.

 

Is a dahlia tuber ruined if it has shriveled? is an Alabama Extension publication which answers this question that it depends how shriveled.