text: 'use strict';
  
  var mongoose = require('mongoose');
  
  var Schema = mongoose.Schema;
  
  var usedBookSchema = new Schema({ 
  	condition	: Number, 
  	price		: Number,
  	seller		: { type: Schema.Types.ObjectId, ref: 'User' }
  });
  
  var UsedBookModel = mongoose.model('UsedBook', usedBookSchema);
  
  var bookSchema = Schema({
  	title		: String,
  	isbn		: Number,
  	description    : String, 
  	usedBookList : [{ type: Schema.Types.ObjectId, ref: 'UsedBook' }]
  });
  
  var BookModel = mongoose.model('Book', bookSchema);
  
  module.exports = BookModel;