How to efficiently get a collection that contains multiple nested collections
<p><em>Title might not be the best, an improvement would be much appreciated!</em></p>

<p>What i mean is actually very simple question:</p>

<p>Say i have a <code>School</code> class containing an array of <code>Student</code>s that has an array of <code>Notebook</code>s, and i want to refer all the <code>Notebook</code>s in my <code>School</code></p>

<pre><code>public class School{
  students: Student[];
}

public class Student{
  notebooks: Notebook[]
}
</code></pre>

<p>How should i refer to all of the Notebooks in my school?</p>

<p><em>Looking for a more efficient way from saving all the <code>Notebook</code>s in a separate array achieved with a <code>for</code> loop..</em></p>

<p>Thanks in advance :)</p>