user22057: This is part (bad) news, part question. The publishers of Berg et al., Biochemistry have withdrawn the title from NCBI Bookshelf:

This raises the question of what to do about all my answers that have (now dead) links to this. I suppose I should check them and edit if they do not stand by themselves.
A great pity, because, although there are good texts on Molecular and Cell Biology on NCBI Bookshelf, there are no alternatives of this standard for Biochemistry there or elsewhere on the Internet to my knowledge.

user16866: As great as it is to link to an outside reference (thanks for doing that!), I don't think it's absolutely necessary if you provide a citation.
As such: Although not the best solution, I think as long as you provide a full citation and make sure your answer is complete without needing to go to the external link, then you've done your due diligence. If that's the case -- well, then sometimes links go dead -- Oh well.

I haven't looked at your Berg-linking answers, so I'm not sure how this recommendation would play out for you. However, I think it provides the minimum (though adequate) amount of effort -- especially if you've already adequately cited the textbook within the question.

I would, however, encourage you to find an alternative link for perhaps 1-2 posts per week or month to spread the editing load, and just slowly update dead links that way.
I know you're not interested in linking to illegitimate copies of published works, so you might not have much of a choice to move on in this case...

user9943: First off, the edition is about 2 decades old and it may not be best practice to cite such a dated work in your answers. But I agree that it may still be appropriate to use it as a reference for basic concepts on Biochemistry. I myself have cited an old edition of Neuroscience of Purves (2002) on the NCBI bookshelf quite a few times in my answers as a reference to basic concepts that are not subject to change over time.
Concerning the dead link, I guess editing your questions would be best, but given you have 550+ answers this likely becomes an overly burdensome task. I wouldn't know of an easy way to filter out all your answers that cite the work. Perhaps filtering them by the tag biochemistry, or related tags would be of any help? At best you are left with a couple of handfuls of questions.
On the bright side; I found a full pdf on Google books of your edition, as well as a pdf of the 8th edition with just a cursory search on Google. Perhaps you can find even newer versions floating around with a more thorough search. How legitimate these copies are would need further investigation, because I would strongly discourage citing illegitimate copies of a book. It is also important to attempt to find a stable internet source for the book which can be  expected to keep the book online for a decent amount of time to prevent the same issue from occurring in the future.
If you can find a decent replacement copy of the book, it may help you in the end in your quest solving the issue. It would greatly benefit your answers I think to use the newest version out there when you're on it.

22057: <p>This is part (bad) news, part question. The publishers of Berg <em>et al.</em>, Biochemistry have withdrawn the title from NCBI Bookshelf:</p>
<p><a href="https://i.stack.imgur.com/io5PF.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/io5PF.png" alt="Berg withdrawn from NCBI Bookshelf" /></a></p>
<p>This raises the question of what to do about all my answers that have (now dead) links to this. I suppose I should check them and edit if they do not stand by themselves.</p>
<p>A great pity, because, although there are good texts on Molecular and Cell Biology on NCBI Bookshelf, there are no alternatives of this standard for Biochemistry there or elsewhere on the Internet to my knowledge.</p>
 16866: <p>As great as it is to link to an outside reference (thanks for doing that!), I don't think it's absolutely necessary if you provide a citation.</p>
<p>As such: Although not the <em>best</em> solution, I think as long as you provide a full citation and make sure your answer is complete without <em>needing</em> to go to the external link, then you've done your due diligence. If that's the case -- well, then sometimes links go dead -- Oh well.</p>
<ul>
<li>I haven't looked at your Berg-linking answers, so I'm not sure how this recommendation would play out for you. However, I think it provides the minimum (though adequate) amount of effort -- especially if you've already adequately cited the textbook within the question.</li>
</ul>
<p>I would, however, encourage you to find an alternative link for perhaps 1-2 posts per week or month to spread the editing load, and just slowly update dead links that way.</p>
<p>I know you're not interested in linking to illegitimate copies of published works, so you might not have much of a choice to move on in this case...</p>
 9943: <p>First off, the edition is about 2 decades old and it may not be best practice to cite such a dated work in your answers. But I agree that it may still be appropriate to use it as a reference for basic concepts on Biochemistry. I myself have cited an old edition of <a href="https://www.ncbi.nlm.nih.gov/books/NBK10799/" rel="nofollow noreferrer">Neuroscience of Purves (2002)</a> on the NCBI bookshelf quite a few times in my answers as a reference to basic concepts that are not subject to change over time.</p>
<p>Concerning the dead link, I guess editing your questions would be best, but given you have 550+ answers this likely becomes an overly burdensome task. I wouldn't know of an easy way to filter out all your answers that cite the work. Perhaps filtering them by the tag <a href="https://biology.stackexchange.com/questions/tagged/biochemistry" class="post-tag" title="show questions tagged &#39;biochemistry&#39;" rel="tag">biochemistry</a>, or related tags would be of any help? At best you are left with a couple of handfuls of questions.</p>
<p>On the bright side; I found a <a href="https://drive.google.com/file/d/0B9Hi1Cy7Y34ERXJJXzRGSjd5bm8/view?resourcekey=0-SgrHs9064AQKVk4Go-65mw" rel="nofollow noreferrer">full pdf on Google books</a> of your edition, as well as <a href="https://www.academia.edu/38170707/Biochemistry_8th_ed_pdf" rel="nofollow noreferrer">a pdf of the 8<sup>th</sup> edition</a> with just a cursory search on Google. Perhaps you can find even newer versions floating around with a more thorough search. How legitimate these copies are would need further investigation, because I would strongly discourage citing illegitimate copies of a book. It is also important to attempt to find a stable internet source for the book which can be  expected to keep the book online for a decent amount of time to prevent the same issue from occurring in the future.</p>
<p>If you can find a decent replacement copy of the book, it may help you in the end in your quest solving the issue. It would greatly benefit your answers I think to use the newest version out there when you're on it.</p>
