Va. Code § 8.01-401.1
In any civil action any expert witness may give testimony and render an opinion or draw inferences from facts, circumstances or data made known to or perceived by such witness at or before the hearing or trial during which he is called upon to testify. The facts, circumstances or data relied upon by such witness in forming an opinion or drawing inferences, if of a type normally relied upon by others in the particular field of expertise in forming opinions and drawing inferences, need not be admissible in evidence.
The expert may testify in terms of opinion or inference and give his reasons therefor without prior disclosure of the underlying facts or data, unless the court requires otherwise. The expert may in any event be required to disclose the underlying facts or data on cross-examination.
To the extent called to the attention of an expert witness upon cross-examination or relied upon by the expert witness in direct examination, statements contained in published treatises, periodicals or pamphlets on a subject of history, medicine or other science or art, established as a reliable authority by testimony or by stipulation, shall not be excluded as hearsay. If admitted, the statements may be read into evidence but may not be received as exhibits. If the statements are to be introduced through an expert witness upon direct examination, copies of the specific statements shall be designated as literature to be introduced during direct examination and provided to opposing parties 30 days prior to trial unless otherwise ordered by the court.
If a statement has been designated by a party in accordance with and satisfies the requirements of this section, the expert witness called by that party need not have relied on the statement at the time of forming his opinion in order to read the statement into evidence during direct examination at trial.
Va. Code § 8.01-401.1