San Francisco: Billionaire entrepreneur Elon Musk, who is attempting to walk away from his deal to acquire Twitter Inc, is seeking documents from advertising technology firms as part of his quest to gain more information on bot and spam accounts on Twitter, according to filings in a Delaware court on Thursday. Twitter has sued the Tesla chief executive, who has accused Twitter of hiding information about how it calculates the percentage of bots on the service, for attempting to walk away from the $44 billion agreement. A trial is scheduled for Oct. 17. Musk's lawyers have subpoenaed both Integral Ad Science (IAS) and DoubleVerify for any documents or communications on their involvement in reviewing accounts or participation in any audit of Twitter's user base. IAS and DoubleVerify, which are both based in New York, use technology to independently verify that digital ads are viewed by real people.