Unable to link models.py

I started building my first Django app and created different models, but when I run

python manage.py validate or python manage.py sqlall books

it shows error as: import error : no module named books

Mostly, I have included the books app correctly in installed apps in settings.py, but still it is not working.

Here are my files-

-----------models.py---------

from django.db import models

# Create your models here.
class publisher(models.Model):
    name= models.CharField(max_length=30)
    address=models.CharField(max_length=50)
    city=models.CharField(max_length=50)
    state=models.CharField(max_length=50)
    country=models.CharField(max_length=50)
    website=models.CharField(max_length=50)

    def __str__(self):
        return self.name


class authors(models.Model):
    salutation= models.CharField(max_length=30)
    name=models.CharField(max_length=50)
    email=models.EmailField()
    headshot=models.ImageField(upload_to='/tmp')

    def __str__(self):
        return self.name

class book(models.Model):
    title=models.CharField(max_length=50)
    author=models.ForeignKey(authors)
    publisher=models.ManyToManyField(publisher)
    publisher_date=models.DateField()

    def __str__(self):
        return self.title
    #code

----------------------------settings.py-------------

"""
Django settings for mytimesite project.

Generated by 'django-admin startproject' using Django 1.8.5.

For more information on this file, see
http://ift.tt/1CMZftV

For the full list of settings and their values, see
http://ift.tt/1EF8H8q
"""

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
import os

BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))


# Quick-start development settings - unsuitable for production
# See http://ift.tt/1CMZfK9

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = '9@dol-1eeeo8j=lcot#=ab7vg=+&(fg8b(+4=o$d1lofrm1j0&'

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = []


# Application definition

INSTALLED_APPS = (
    #'django.contrib.admin',
    #'django.contrib.auth',
    #'django.contrib.contenttypes',
    #'django.contrib.sessions',
    #'django.contrib.messages',
    #'django.contrib.staticfiles',
    'mytimesite.books',
)

MIDDLEWARE_CLASSES = (
    #'django.contrib.sessions.middleware.SessionMiddleware',
    #'django.middleware.common.CommonMiddleware',
    #'django.middleware.csrf.CsrfViewMiddleware',
    #'django.contrib.auth.middleware.AuthenticationMiddleware',
    #'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
    #'django.contrib.messages.middleware.MessageMiddleware',
    #'django.middleware.clickjacking.XFrameOptionsMiddleware',
    #'django.middleware.security.SecurityMiddleware',
)

ROOT_URLCONF = 'mytimesite.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': ['/home/sidharth/Desktop/newproject/mytimesite/templates'],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                #'django.template.context_processors.debug',
                #'django.template.context_processors.request',
                #'django.contrib.auth.context_processors.auth',
                #'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'mytimesite.wsgi.application'


# Database
# http://ift.tt/1EF8GkO

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}


# Internationalization
# http://ift.tt/1LbgPfE

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# http://ift.tt/1EF8GkR

STATIC_URL = '/static/'

Here's where models.py is located:

newproject>mytimesite>books>modules.py

where newproject contains bin and stuff. mytimesite contains manage.py and books is the app.