protected function formatGedcomMonth(): string
    {
        // Our simple lookup table doesn't work correctly for Adar on leap years
        if ($this->month === 7 && $this->calendar instanceof JewishCalendar && !$this->calendar->isLeapYear($this->year)) {
            return 'ADR';
        }

        return array_search($this->month, static::MONTH_ABBREVIATIONS, true);
    }