In addition to a disclosure request served under Section 301.051, a party may obtain discovery by oral deposition and a report prepared in accordance with Section 301.105 of:
(1) the subject matter on which a testifying expert is expected to testify;
(2) the expert's mental impressions and opinions;
(3) the facts known to the expert, regardless of when the factual information is acquired, that relate to or form the basis of the expert's mental impressions and opinions; and
(4) other discoverable items, including documents not produced in response to a disclosure request.