The first link is to a study in 1990, nearly two decades ago.  What does it demonstrate? I've only accessed the abstract, and it seems to be talking about a technique that was used on subjects in that study, possibly as a trial of a new procedure; it's not clear from that abstract whether the procedure mentioned is used regularly (and if so, in what countries and during what decades). ☺    

 ::I have read the full "first study" , and it is regularly used and thus described for edification in the US.  The procedure (frenectomy) is to alleviate frenular chordee resulting from elective circumcisions.