http://dx.doi.org/10.1016/j.ipm.2007.02.007 has been crawled 45 times going all the way back to June 30, 2009.

A crawl can be a duplicate of the last one. It happens about 25% of the time across 420,000,000 websites. FAQ

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Note

This calendar view maps the number of times http://dx.doi.org/10.1016/j.ipm.2007.02.007 was crawled by the Wayback Machine, not how many times the site was actually updated. More info in the FAQ.