It appears to go back to the 1970 "Catalogue of Star Clusters and Associations" by Alter, Ruprecht and Vanysek and updated with a 1981 supplement.
Here's the SIMBAD page describing these catalogues.
The complete list of all GCL objects is
here. Instead of 125, it actually includes 132 objects, as some were apparently added in the supplement (e.g. GCL 43.1 = Terzan 3). Just click on any name and you'll get data on the cluster, included all the aliases, so you can fill in your missing numbers.