Bosch, Gerhard; Kalina, Thorsten; Weinkopf, Claudia - In: Journal for Labour Market Research 45 (2012) 3/4, pp. 209-231
"The commercial cleaning industry is characterized by a high proportion of labour costs and a pronounced comparability and standardization of services. The statistical preconditions for the evaluation have not been ideal which is mainly due to the high proportion of part-time work and mini-jobs....