public static function cWeekBeginning($year, $cWeek = 0) {
		if ($cWeek <= 1 || $cWeek > static::cWeeks($year)) {
			$first = mktime(0, 0, 0, 1, 1, $year);
			$wtag = (int)date('w', $first);

			if ($wtag <= 4) {
				/* Thursday or less: back to Monday */
				$firstmonday = mktime(0, 0, 0, 1, 1 - ($wtag - 1), $year);
			} elseif ($wtag != 1) {
				/* Back to Monday */
				$firstmonday = mktime(0, 0, 0, 1, 1 + (7 - $wtag + 1), $year);
			} else {
				$firstmonday = $first;
			}
			return $firstmonday;
		}
		$monday = strtotime($year . 'W' . static::pad($cWeek) . '1');
		return $monday;
	}