Searching and researching about solfège methods.

[gustavob]

I'm searching for solfège methods and until now, I know 3 of them:

• Music for Sight Singing - Ottman
• Pascoale Bona
• Dannhöuser

And I have some questions:

• Are there more solfège methods?
• I've read that P. Bona is an obsolete solfêge method, why?
• They also say that Ottman's book is way better, why?

[keyboardclass]

I use Trinity's Sound at Sight.

[gustavob]

Oh, thanks for the suggestion, i've also discovered:
Progressive sight singing - Carol K