When I load revision history in Google Docs, it does not change the URL. Is it possible to link to a history entry in Google Docs?
For files that were uploaded to Google Drive: yes, this is directly supported (as explained in the official help regarding file versions). Select the "Manage revisions" menu-item for the uploaded file, available either by right-clicking on it, or by selecting it and then expanding the "More" dropdown menu. A separate permalink will be available for each individual revision.
For files that were created in Google Drive (as a "Document", "Presentation", "Spreadsheet", ... etc.): this is not directly supported, because the individual items inside the "Revision history" do not have associated permalinks. However, as was mentioned in a previous comment, for any of the previous snapshots, you can temporarily restore to that version and copy it to a new file (whose name can include a version number or timestamp), with its own URL.