public class Customer
    {
        public int Id { get; set; }

        public string Name { get; set; }

        public virtual ICollection<Document> Documents { get; set; }
    }

public class Document
    {
        public int Id { get; set; }

        public string Name { get; set; }

        public ICollection<Customer> Customers { get; set; }
    }

public class DbSampleMtM : DbContext
    {
        public DbSet<Customer> Customers { get; set; }

        public DbSet<Document> Documents { get; set; }

        protected override void OnModelCreating(DbModelBuilder builder)
        {
            base.OnModelCreating(builder);

            builder.Entity<Customer>()
                .HasMany(c => c.Documents)
                .WithMany(d => d.Customers)
                .Map(m => m.ToTable("TB_LINKS"));
        }

    }