COUNTRY ENCYCLOPEDIAS: There are many encyclopedias about the culture and history of specific countries and regions of the world. While they are not solely focused on dance, you can oftentimes find some good specific dance and performing arts information there. Try searching in Library Search for the name of the country and the word "encyclopedias."
LINER NOTES: The booklets/liner notes that accompany many CDs can be an extremely valuable source of information. When watching/listening to some of the resources in Step 3 make sure to read the liner notes available through the resource. They can often be found under a tab labeld "related documents," "accompany documents," "booklet," etc.