AOL Time Warner is shopping its book publishing unit, including Little, Brown, & Co. and Warner Books, according to published reports.  The step is one of several potential asset sales the company is exploring to reduce debt.  Long term debt on the company's most recent balance sheet totaled over $28 billion out of a total $62 billion in liabilities.  Other assets on the block reportedly include its sports teams, Comedy Central and Court TV.  It is also planning a public offering in its cable unit later this year.  Warner Books is important to Big Four comic publisher DC comics because it represents its avenue to the book trade, where it was the top graphic novel publisher until recent years, when manga began blowing U.S. material out of the water (e.g., see 'Manga Dominate Graphic Novel Sales in Bookstores').