Laravel: Join between 4 tables using Eloquent

I'm new to Laravel and I've some doubt about Eloquent, I would like to create a join between 4 tables like these:

-A
id

-B
id

-C
id

-J
id, A_id, B_id, C_id

Obviously every table has a corresponding model...

How can I do a join between all these tables using Eloquent?

via Chebli Mohamed