en_btr_backend/app/Book.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Book extends Model
{
    public $fillable = [
        'name'
    ];

    public $visible = [
        'name'
    ];

    /**
     * @return \Illuminate\Database\Eloquent\Relations\HasMany
     */
    public function chapters()
    {
        return $this->hasMany(Chapter::class);
    }
}