The Adventist Archives website provides hundreds of documents for study. I have made use of the Review and Herald documents and the General Conference Bulletins, thus far.
On the White Estate site, the two features I use the most are:
This feature makes possible topical studies within Ellen White’s writings. I also use it to identify the document providing the context for specific quotes. Once I have the name of the document then I will go to the GUI feature and examine the context.
This feature provides an amazingly comprehensive source of Ellen G. White material.