Apple’s iTunes, iBookstore and Apple App Store is expected to grow at a rate of about 39% over the next three years and may contribute about US$13 billion in revenues in fiscal 2013, Global Equities Research analyst Trip Chowdry tells clients in a note, as reported by the “International Business Times” (http://macte.ch/YgjTf).

In addition, the analyst adjusted his estimates on Apple to reflect a strong back to school sales of Macs. He’s also expecting market share wins of Apple in the enterprise.

For the third quarter, Chowdhry now expects revenues of $24.80 billion and earnings of $5.81 a share, reflecting a year-over-year increase of 58% and 65%, respectively. Wall Street expects Apple to earn $5.69 a share on revenue of $24.67 billion, according to analysts polled by Thomson Reuters.