What is the test for establishing that a verified memorandum is prima facie evidence of proper charges?

"'[I]f the items appear to be proper charges, the verified memorandum is prima facie evidence that the costs, expenses and services therein listed were necessarily incurred by the [party] [citations], and the burden of showing that an item is not properly chargeable or is unreasonable is upon the [objecting party].' [Citations.]" (Nelson v. Anderson (1999) 72 Cal.App.4th 111, 131.) "The court's first determination, therefore, is whether the statute expressly allows the particular item, and whether it appears proper on its face. [Citation.] If so, the burden is on the objecting party to show them to be unnecessary or unreasonable. [Citation.]" (Ibid.)