Search plp.org

your best bet is to try searching Altavista.
they've always got their robots crawling all over the place.
Keep the host:plp.org prefix as that makes it so that you search PLP's site using their search engine.

Search and Display the Results
   

NOTE: Use Altavista's search parameters. So, to search for the word "oil", leave a space after the "plp.org" and then type in +oil   

To search for a multiword phrase, surround the phrase in quotation marks: +"pipeline politics". And so forth.