California Code, Revenue and Taxation Code - RTC § 6006.1

The granting of possession of tangible personal property by a lessor to a lessee, or to another person at the direction of the lessee, is a continuing sale in this state by the lessor for the duration of the lease as respects any period of time the leased property is situated in this state, irrespective of the time or place of delivery of the property to the lessee or such other person.