I'm trying to modify a label in a calendar view. This label uses to appear in every calendar view, just below the minicalendar on the right side of the screen. Obviously, the string of the label is different depending on the selected calendar view. In my case, I would like to change the label which appears in the calendar view of the section opportunities (crm). The label is Salesperson. I have located the file which contents the code of the calendar view, but this one is composed by only a few lines:

<!-- CRM Lead Calendar View -->
<record model="ir.ui.view" id="crm_case_calendar_view_leads">
    <field name="name">CRM - Leads Calendar</field>
    <field name="model">crm.lead</field>
    <field name="priority" eval="2"/>
    <field name="arch" type="xml">
        <calendar string="Leads Generation"
            date_start="date_action" color="user_id">
            <field name="name"/>
            <field name="partner_name"/>
        </calendar>
    </field>
</record>

And here there are not any Salesperson strings. Where is it?