While scientific evidence has proven that women have a falsetto register, the issue of 'female falsetto' has been met with controversy among teachers of singing. This controversy does not exist within the sciences and arguments against the existence of female falsetto do not align with current physiological evidence. Some pioneers in vocal pedagogy, like Margaret Green and William Vennard, were quick to adopt current scientific research in the 1950s, and pursued capturing the biological process of female falsetto on film. They went further to incorporate their research into their pedagogical method of teaching female singers. Others refused to accept the idea, and opposition to the concept of female falsetto has continued among some teachers of singing long after scientific evidence had proven the existence of female falsetto. Celebrated opera singer and voice teacher Richard Miller pointed out in his 1997 publication National Schools of Singing: English, French, German, and Italian that while the German school of voice teachers had largely embraced the idea of a female falsetto into pedagogical practice, there is division within the French and English schools and a complete rejection of the idea of female falsetto in the Italian school of singing. In his 2004 book, Solutions for Singers: Tools For Performers and Teachers, Miller said, "It is illogical to speak of a female falsetto, because the female is incapable of producing a timbre in the upper range that is radically different from its mezza voce or voce piena in testa qualities".