What has the author P M Erdniev written?

There is no author named "P M Erdniev" that appears to be known or published. It's possible there's a typo in the name or that the author publishes under a different name.

Could you please double-check the spelling or provide any other information about the author, such as the genre they write in, their nationality, or any specific titles you may have heard of?

This information will help me identify the author you're looking for and provide you with a list of their works.