how to share multiple volumes in docker compose code example

Example: share volume between containers docker-compose

services:
    nginx:
        build: ./nginx/
        ports:
            - 80:80
        links:
            - php
        volumes:
            - app-volume:location_in_the_container

    php:
        build: ./php/
        expose:
            - 9000
        volumes:
            - app-volume:location_in_the_container

volumes:
     app-volume: