Some styles - such as APA - include a reference's DOI when displaying it as a bibliography entry. Many users prefer for this item to be removed and this can be achieved by modifying the style.
1. As before, we need to open the APA style for editing using the CSL Editor. You can find the steps for this in the first section of this guide - an overview of the CSL Editor.
2. Once the style has opened in the editor, we can see that DOIs are being displayed against each bibliography entry. As these are the elements that we wish to remove, we can start by clicking on one of them to select it. This will give us some information about where the DOI can be found within the style.
3. Selecting the DOI highlights it in the Example Panel and causes the Style Overview to display its location. We can see from the tree structure of the Style Overview that the DOI is 'called' as part of a series of conditional arguments. A style is compiled of a series of these queries and instructions - which follow the standard logic format of IF (X) THEN (Y) ELSE (Z). With styles these arguments usually apply to the type of document which is applied to a reference - is it a book? Is it a journal article? And so on.
In this case, we can see that the argument can be read as 'IF the reference is anything other than a thesis, AND IF the reference contains a DOI THEN display DOI'.
It's important to note that this is just a fraction of the whole argument - there needs to be an extra component to provide instructions for what to do in the case that the reference does not contain a DOI and, indeed, if we look at the style we can see that this is the case - in the event that that a reference does not contain a DOI, a further conditional exists to check if the reference is a webpage and applies further instructions depending on the outcome.
4. We therefore need to ensure that when we remove the DOI element we are not leaving an incomplete argument, as this will render the style invalid. To this end, we need to move the webpage conditional higher up the style to take the place of the DOI query.
To do this, using the Style Overview panel, just drag and drop the Conditional node for 'if webpage' above the existing Conditional node for 'if DOI'.
When moving nodes it's important to position them precisely, since attempting to locate one in an improper location can render your style invalid. Look out for the green check mark next to your cursor which indicates that the node you're relocating will be accepted where you're attempting to place in. You can use Edit > Undo if you accidentally drop a node in the wrong place.
5. The DOI Conditional node can now be safely deleted by clicking to highlight it and using the minus button ('-') in the top right corner of the Style Overview panel.
You should see the DOIs disappear from the bibliography entries in the Example Panel.