Is this a mistake?

[irmamar]

Noooo, I can't throw my book away. It's been written by my teacher, who studied in a well-known British University, is a doctor and has written several books about learning English. Now I'm sure that it's a typo, although I think I don't have so much printer's errors in my book . I'm not going to discuss if "would had" is widely used somewhere, because I think that such matter may be studied in upper levels, not in mine.

And now, well, I must go on studying.

Thank you everybody.