function init() {
		$_option = $this->getSlug();
		$_page = $_option;
		$_section = $this->getSlug() . '_section';

		add_settings_section(
			$_section,
			'',
			[ $this, 'display' ],
			$_page
		);

		add_settings_field(
			'amazon',
			__( 'Amazon URL', 'pressbooks' ),
			[ $this, 'renderAmazonField' ],
			$_page,
			$_section
		);

		add_settings_field(
			'oreilly',
			__( 'O\'Reilly URL', 'pressbooks' ),
			[ $this, 'renderOReillyField' ],
			$_page,
			$_section
		);

		add_settings_field(
			'barnesandnoble',
			__( 'Barnes and Noble URL', 'pressbooks' ),
			[ $this, 'renderBarnesAndNobleField' ],
			$_page,
			$_section
		);

		add_settings_field(
			'kobo',
			__( 'Kobo URL', 'pressbooks' ),
			[ $this, 'renderKoboField' ],
			$_page,
			$_section
		);

		add_settings_field(
			'ibooks',
			__( 'iBooks URL', 'pressbooks' ),
			[ $this, 'renderiBooksField' ],
			$_page,
			$_section
		);

		add_settings_field(
			'otherservice',
			__( 'Other Service URL', 'pressbooks' ),
			[ $this, 'renderOtherServiceField' ],
			$_page,
			$_section
		);

		register_setting(
			$_page,
			$_option,
			[ $this, 'sanitize' ]
		);
	}