A specific example of the problem can be given for a 2017 Nature Disease Primer article on new antimalarial compounds entering development . Because the chemistry representations were restricted only to images in the PDF a blog post was necessary to manually map the structures to PubChem identifiers . The MyNCBI link to the 16 CID entries given at the top of the blog post are still live ( indicating reassuring persistence for this system after four years). While this initial connectivity was only D-C (and where D was a review article rather than a primary activity report) this example had an important sequel.