You can read more about the Yinggarda language in the following books and articles. For some of them a downloadable PDF is available and this is indicated by a clickable link.
Austin, Peter. 1988. Aboriginal Languages of the Gascoyne-Ashburton Region. La Trobe Working Papers in Linguistics 1, 43-63. La Trobe University. [downloadable from here]
Austin, Peter K. 1992. A dictionary of Yinggarda, Western Australia. La Trobe University, Department of Linguistics. xii+69pp.
Daisy Bates. 1985. The native tribes of Western Australia. Canberra: National Library of Australia. xii+387pp.
Dench, Alan Charles. 1998. Yingkarta. (Languages of the World / Materials, 137.) München: Lincom Europa. 75pp.
These websites may be useful: Glottolog Wikipedia Endangered Languages Project