Johnathon Williams

This plugin removes the ability for contributors to view or edit scheduled posts. It works by removing scheduled posts from the contributor’s list of posts in the posts admin list.

Restrict Contributors from Scheduled Posts

Restricts contributors from viewing or editing their posts after the posts are scheduled to publish.

sujitkumar87

WP Post Contributors plugin allows you to add more than one author to the post who have contributed. 
The contributors meta will apear just aside of your post body. Just check the authors who have contibuted. 
And update the post to save it.
Features of Custom News Widget:
<ul>
<li>User friendly and easy to use.</li>
<li>Tested with other popular plugins.</li>
<li>Add authors to the post easily.</li>
</ul>

WP Post Contributor

WP Post Contributors plugin allows you to add more than one author to the post who have contributed.

Restrict Contributors from Scheduled Posts vs WP Post Contributor