Does secondary evidence of the contents of a writing need to be received in writing?

The holding in Heaps, supra, 124 Cal.App.4th 286 comports with the well-settled rule that "secondary evidence of the contents of a writing may be received where the writing consists of numerous accounts or other documents which cannot be examined in court without great loss of time, and the evidence sought from them is only the general result of the whole. In such case the results of an examination made by a qualified person of such books and documents may be proved by his testimony." (Sachs v. Killeen (1958) 165 Cal.App.2d 205, 214, italics added.)