PHP Laravel 5.5: How to get the object name of a class that is invoked using dependency injection using Reflection

I am using PHP Reflection to read a file. In that file, there are two classes are passed as a dependency like following:

private $books;
private $genres;

function __construct(Book $books, Genre $genres)
{
    $this->books= $books;
    $this->genres= $genres;
}

I can get the type and name of the constructor parameters like this.

$class = new ReflectionClass('AdminClass'); 

$parameters = $class->getConstructor()->getParameters();

foreach ($parameters as $param) {
    echo $parameter->name."<br>";
    echo $param->getType()."<br>";
}

Now, i want to get the object where the specific class is instantiated. Such as, here, inside the constructor $this->books represents as a Book class object, $this->genres represents Genre class object.

So i want to get $this->books.

How can i get the objects names ?