public function getSource($sourceName = null) {
		if ($sourceName === 'default') {
			$sourceName = null;
		}

		foreach ($this->sources as $key => $item) {
			if ((!$sourceName || $sourceName === $key)) {
				return $item;
			}

			$source = $item !== $this ? $item->getSource($sourceName) : null;

			if ($source) {
				return $source;
			}
		}

		if ($sourceName) {
			return null;
		}

		return $this;
	}