NEW YORK - The missing sales numbers are coming back on

Two days after Amazon said a "glitch" had caused the sales rank to be dropped from thousands of books, the numbers returned Tuesday for Annie Proulx's "Brokeback Mountain," James Baldwin's "Giovanni's Room" and other notable titles.

Some authors whose rankings were dropped have posted messages from Amazon that said their books had been categorized as "Adult" and were being removed from some bestseller lists and search functions. Amazon's actions led to a furious stream of responses on Twitter and elsewhere online.

Amazon has yet to comment on the author messages, but on Monday called the deletions an "embarrassing and ham-fisted cataloguing error" and promised "to implement new measures" to prevent them in the future.