How to use the keyword 'references' in MySQL?

Here is an example directly from MySQL website:

CREATE TABLE parent (id INT NOT NULL,
                     PRIMARY KEY (id)
) ENGINE=INNODB;

CREATE TABLE child (id INT, parent_id INT,
                    INDEX par_ind (parent_id),
                    FOREIGN KEY (parent_id) REFERENCES parent(id)
                    ON DELETE CASCADE
) ENGINE=INNODB;

Create the hobby table similarly to this:

CREATE TABLE hobby (
  id INT NOT NULL AUTO_INCREMENT,
  person_id INT NOT NULL,
  hobby_name VARCHAR(255),
  PRIMARY KEY(id),
  FOREIGN KEY(person_id) REFERENCES person(id))