Update link to IMS2 on Amazon

index.qmd

@@ -16,7 +16,7 @@ The book will always be available for free here. It is also available in PDF (fo
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 <a href="https://leanpub.com/imstat" target="_blank"><img src="images/_icons/file.png" width="30px">&nbsp;<strong>Download PDF</strong></a>
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-<a href="https://www.openintro.org/go?id=ims1_bw_pb&referrer=/book/ims/online"><img src="images/_icons/book.png" width="30px">&nbsp;<strong>Purchase paperback</strong></a>
+<a href="https://www.openintro.org/go?id=ims2_bw_pb&referrer=/book/ims/online"><img src="images/_icons/book.png" width="30px">&nbsp;<strong>Purchase paperback</strong></a>
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