According to internal documents obtained by the website TechCrunch, Microsoft has offered $1 billion for the digital assets of Nook Media, Barnes & Noble's digital book venture. The deal would give Microsoft Barnes & Noble's e-books, homegrown games and of course its Nook e-readers and tablets.

But perhaps not for long: Nook plans to discontinue its Android-based tablet business by the end of 2014, according to the documents. Instead, the company will transition to having Nook content available solely on third-party devices, perhaps ones made by Microsoft, if the purchase goes through.

Digital Book World speculated in February that the Nook e-readers seem destined to be discontinued -- though not necessarily right away.

Microsoft started working with Barnes & Noble in April 2012 with a $300-million investment, which included $180 million to develop Nook content for Windows 8 tablets, including Microsoft's own Surface tablet

TechCrunch says the documents it obtained value Barnes & Noble at $1.66 billion -- about what the Nook Media division alone was said to be worth when it was first formed. Still, the TechCrunch report, posted late Wednesday, sent Barnes & Noble's stock price up about 20% in early trading Thursday.

There have been 10 million Nook devices sold to date, and the company has 7 million subscribers. The newest models have recently been discounted for Mother's Day.

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