It is estimated that there are professional paper writers downstairs, and it is true to solicit business, but you can't deliberately answer wrong and be irresponsible in order to earn a little money.
By the way, those who can subscribe to the post office, those who can publicly issue and sell, and those who can publicly advertise all have CN numbers in principle, otherwise it will be illegal.
Beware of some illegal magazines with serial numbers and collect money to distribute papers.