"The piezoelectric resonator 10 may be preferably mounted on the insulating substrate 62 so that two protrusions 70 made from an electrically conductive material such as electrically conductive adhesive are provided on both pattern electrodes 66 and 68, and the external electrodes 20 and 22 of the piezoelectric resonator 10 are connected to the two protrusions 70, as shown in FIGS. 31 and 32." . . . .