In the absence of an agreement as provided for in Article L. 3123-20, the number of overtime hours worked by a part-time employee during the same week or month or over the period provided for by a collective agreement concluded on the basis of Article L. 3121-44 may not exceed one tenth of the weekly or monthly working hours provided for in his contract and calculated, where applicable, over the period provided for by a collective agreement concluded on the basis of the same Article L. 3121-44.