app.js

// ./app.js
[..]
var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/kittens');
[..]
app.use('/', routes);
app.use('/find', find);
[..]

books.js

// ./models/books.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var Books = new Schema({
	title: {type: String, required: true, unique: true},
	description: {type: String, required: true},
	cover: String,
});

module.exports = mongoose.model('Books', Books);