Call to undefined relationship [title] on model [App\Models\Employee]

working with Laravel 9 and in My App there are Relationship one to many with Employee Model ans Title and Salary. Employee.php

class Employee extends Model
{
    use HasFactory;

    public function titles(): HasMany
    {
        return $this->hasMany(Title::class, 'emp_id');
    }

    public function salaries(): HasMany
    {
        return $this->hasMany(Salary::class, 'emp_id');
    }
}

Title.php

public function employee(): BelongsTo
    {
        return $this->belongsTo(Employee::class, 'emp_no');
    }

Salary.php

 public function employee(): BelongsTo
    {
        return $this->belongsTo(Employee::class, 'emp_no');
    }

now I am going to get all data using EmployeeController getEmployee function as well EmployeeController.php

use Illuminate\Http\Request;
use App\Models\Employee;
use App\Models\Title;
use App\Models\Salary;


class EmployeeController extends Controller
{
    public function getEmployee() {
        return response()->json(Employee::with('title','salary')->get(), 200);
      
    }
}

and My api.php call is like this

Route::get('employees','App\Http\Controllers\EmployeeController@getEmployee');

but result shown following error message as well

Illuminate\Database\Eloquent\RelationNotFoundException: Call to undefined relationship [title] on model [App\Models\Employee]. in file 

how to fix this?