Wherever you get your information from it is important that you evaluate the quality of the information. There are many factors that you need to consider when assessing the quality of the information, such as currency, the authority of the writer ...
Here is a link to the Information Source Evaluation Matrix (click on picture), a useful guide that takes you through the factors you need to consider to assess the quality of information you are relying on.
New York Public Library Dance Research Collection
A searchable catalogue of the Dance Research Collection held at New York Public Library. Use the drop-down menu on the 'Collection' search box to select 'Dance Research Collection' - you will need to scroll down to nearly the bottom of the list.