te Koppele, Johan M, et al. “Development of a Convenient and Sensitive Assay for Matrix Metalloproteinase Enzyme Activity in Synovial Fluid Samples Using Fluorigenic Peptides”. Acta Orthopaedica, vol. 66, no. sup266, Jan. 1995, pp. 151-2, doi:10.3109/17453679509157676.