Don't want iBooks to always paste the "Excerpt From" of what I have copied I read on iBooks, and some other resources and gather my notes in EverNote.
When I copy a text from iBooks to keep it as a note in some other external application like EverNote, it keeps pasting the source info which is so annoying and I have to keep deleting them after every copy-paste. For example:

“To bind this class using Ninject, I specify the value of the constructor parameter using the WithConstructorArgument method in the AddBindings method, as shown in Listing 6-20.”

Excerpt From: Adam Freeman. “Pro ASP.NET MVC 5.” iBooks. https://itunes.apple.com/WebObjects/MZStore.woa/wa/viewBook?id=4CB3769B56E7D2A905C0332D53D7E31D
Here is a solution that requires no third-party software and lets you keep using the standard ⌘C shortcut to copy text in Books.

1. Create a Quick Action “Copy without Citation in Books”


Open Automator and choose File > New (⌘N).
For the type of document, choose Quick Action. This will allow us to create a keyboard shortcut for it later.


Configure the workflow as follows:


Workflow settings


Workflow receives current [text] in [Books]
(Leave the other three settings at the default)

Add in the actions list:


Copy to Clipboard




Use ⌘S to save the Quick Action. Name it “Copy without Citation in Books”.


The “workflow receives current text in Books” setting in the workflow bypasses the clipboard-modifying behavior of Books. Thus, the workflow needs no extra action to strip the text added by Books.

2. Give the Quick Action a keyboard shortcut of ⌘C in Books


Open System Preferences > Keyboard. View the Shortcuts tab and select App Shortcuts on the left.
Click the + button to add a new App Shortcut.
Fill in the sheet as follows:


Application: Books
Menu Title: Copy without Citation in Books
Keyboard Shortcut: ⌘C



Click Add. You will see the shortcut appear in the list:




And you’re done. From now on, when you want to copy your selected text in Books, just press ⌘C and the exact text will be copied.