Man pages matching name geo::helmerttransform in section 3pm:

Geo::HelmertTransform.3pm.en	debian 10 / libgeo-helmerttransform-perl
Geo::HelmertTransform.3pm.en	debian 11 / libgeo-helmerttransform-perl
Geo::HelmertTransform.3pm.en	debian 12 / libgeo-helmerttransform-perl