XPath to select element based on childs child value

Trying to select an element based on the value of one of it's childrens childrens

Thinking the following but not working, appreciate any help, thanks

./book[/author/name = 'John'] or

./book[/author/name text() = 'John']

Want all books where the author name = 'John'

Xml file

<list>
   <book>
      <author>
         <name>John</name>
         <number>4324234</number>
      </author>
      <title>New Book</title>
      <isbn>dsdaassda</isbn>
   </book>
   <book>...</book>
   <book>...</book>
</list>

Almost there. In your predicate, you want a relative path, so change

./book[/author/name = 'John'] 

to either

./book[author/name = 'John'] 

or

./book[./author/name = 'John'] 

and you will match your element. Your current predicate goes back to the root of the document to look for an author.