In California, work product is protected by statute: Code of Civil Procedure section 2018 provides in relevant part that "(a) It is the policy of the state to: (1) preserve the rights of attorneys to prepare cases for trial with that degree of privacy necessary to encourage them to prepare their cases thoroughly and to investigate not only the favorable but the unfavorable aspects of those cases; (2) to prevent attorneys from taking undue advantage of their adversary's industry and efforts.(b) Subject to subdivision (c), the work product of an attorney is not discoverable unless the court determines that denial of discovery will unfairly prejudice the party seeking discovery in preparing that party's claim or defense or will result in an injustice.(c) Any writing that reflects an attorney's impressions, conclusions, opinions, or legal research or theories shall not be discoverable under any circumstances." Work product is defined by case law as "'the product of the attorney's effort, research, and thought in the preparation of his client's case. It includes the results of his own work, and the work of those employed by him or for him by his client, in investigating both the favorable and unfavorable aspects of the case, the information thus assembled, and the legal theories and plan of strategy developed by the attorney -- all as reflected in interviews, statements, memoranda, correspondence, briefs, and any other writings reflecting the attorney's "impressions, conclusions, opinions, or legal research or theories," and in countless other tangible and intangible ways." (BP Alaska Exploration, Inc. v. Superior Court (1988) 199 Cal. App. 3d at pp. 1253-1254, fn.4.) California recognizes that the work-product doctrine "prevents attorneys from taking undue advantage of their adversary's industry and efforts." ( Code Civ. Proc., 2018, subd. (a).) In California, the distinction between "derivative" and "non-derivative" material is the analytic framework applied to determining whether materials are protected by the attorney work-product doctrine. Three levels of protection exist. Core work product, i.e., material solely reflecting an attorney's "impressions, conclusions, opinions, or legal research or theories," is entitled to absolute protection from discovery. ( Izazaga v. Superior Court (1991) 54 Cal. 3d 356, 382, fn. 19, 285 Cal. Rptr. 231, 815 P.2d 304.) Qualified protection exists for work product which is an amalgamation of factual information and attorney thoughts, impressions, conclusions. ( Nacht & Lewis Architects, Inc. v. Superior Court (1996) 47 Cal. App. 4th 214, 217, 54 Cal. Rptr. 2d 575.) Such derivative material would include charts and diagrams, audit reports, compilations of entries in documents, records and other databases, appraisals, opinions, and reports of experts employed as non-testifying consultants. Derivative work product will be ordered disclosed if denial of discovery would unfairly prejudice the other party or result in an injustice. ( Code Civ. Proc., 2018 , subd. (b); BP Alaska Exploration, Inc. v. Superior Court, supra, 199 Cal. App. 3d at p. 1250.) The party seeking disclosure must demonstrate good cause, which involves a balancing of the need for disclosure against the purposes served by the work-product doctrine. ( National Steel Products Co. v. Superior Court (1985) 164 Cal. App. 3d 476, 490, 210 Cal. Rptr. 535.) Lastly, purely factual material receives no work product protection. ( Nacht & Lewis Architects, Inc. v. Superior Court, 47 Cal. App. 4th at pp. 217-218; Rodriguez v. McDonnell Douglas Corp. (1978) 87 Cal. App. 3d 626, 647-648, 151 Cal. Rptr. 399.) The mere fact that a lot of "work" has been put into preparing the materials does not entitle them to work-product protection. Thus, a list of witnesses showing their names and locations is not protected, even where the attorney has spent a lot of time investigating and compiling the list. ( Aerojet-General Corp. v. Transport Indemnity Insurance. (1993) 18 Cal. App. 4th 996, 1004, 22 Cal. Rptr. 2d 862.)