I am often asked about basic entities of ReSharper code model and relations between them. Here is a table that would help to understand basic principles. Read the table below from left to right and then to top. For more infofrmation about the SDK see: this page

	ITreeNode	IReference	IDeclaredElement	IDeclaration
ITreeNode	id	.GetReferences()		node as IDeclaration
IReference	.GetTreeNode()	id	.Resolve().DeclaredElement
IDeclaredElement		IPsiService.Finder.FindReferences(...)	id	.GetDeclarations()
IDeclaration	id		.DeclaredElement	id