Per Sort

 @manual{respect-manual-08,
    author = {Casadei, Matteo and Omicini, Andrea},
    title = {\textsf{{R}e{S}pec{T}} Guide},
    year = 2008
} 

 @manual{bibtex-patashnik88,
    author = {Patashnik, Oren},
    month = {8}}}ing},
    url = {http://mirrors.ctan.org/biblio/bibtex/base/btxdoc.pdf},
    year = 1988
} 

 @manual{bibtexstyles-patashnik88,
    author = {Patashnik, Oren},
    month = {8}}} Styles},
    url = {http://mirrors.ctan.org/biblio/bibtex/base/btxhak.pdf},
    year = 1988
}