I would like to automatize the handling of my bibliographical references once for all, and to achieve this, I would like to use bibtex. I am aware of the existence of various bst files, for various styles of bibliographies: numerical labels, alphanumerical labels etc, but I would like to mix them, and to keep certain bibliographical references always in the same order, and always on the top of my references lists. But I don't know how to do it. I would like the output to look like the bibliography produced by the following LaTeX source code:
\begin{thebibliography}{100}
\addtolength{\leftmargin}{0.2in} % sets up alignment with the following line.
\setlength{\itemindent}{-0.2in}
\bibitem[EGA]{EGA} {\sc A. Grothendieck} et {\sc J. Dieudonn\'e}, \emph{\'El\'ements de g\'eom\'etrie alg\'ebrique, (Publ. Math. I.H.E.S.}, tomes $4$, $8$, $11$, $17$, $20$, $24$, $28$, $32$, $1960$-$1967$).
\bibitem[EGA I]{EGA1} {\sc A. Grothendieck} et {\sc J. Dieudonn\'e}, \emph{\'El\'ements de g\'eom\'etrie alg\'ebrique, I. Le langage des sch\'emas, (Publ. Math. I.H.E.S.}, tome $4$, $1960$).
\bibitem[EGA II]{EGA2} {\sc A. Grothendieck} et {\sc J. Dieudonn\'e}, \emph{\'El\'ements de g\'eom\'etrie alg\'ebrique, II. \'Etude globale \'el\'ementaire de quelques classes de morphismes, (Publ. Math. I.H.E.S.}, tome $8$, $1961$).
\bibitem[EGA III.1]{EGA31} {\sc A. Grothendieck} et {\sc J. Dieudonn\'e}, \emph{\'El\'ements de g\'eom\'etrie alg\'ebrique, III.1. \'Etude cohomologique des faisceaux coh\'erents (Premi\`ere partie), (Publ. Math. I.H.E.S.}, tome $11$, $1961$).
\bibitem[EGA III.2]{EGA32} {\sc A. Grothendieck} et {\sc J. Dieudonn\'e}, \emph{\'El\'ements de g\'eom\'etrie alg\'ebrique, III.2. \'Etude cohomologique des faisceaux coh\'erents (Seconde partie), (Publ. Math. I.H.E.S.}, tome $17$, $1963$).
\bibitem[EGA IV.1]{EGA41} {\sc A. Grothendieck} et {\sc J. Dieudonn\'e}, \emph{\'El\'ements de g\'eom\'etrie alg\'ebrique, IV.1. \'Etude locale des sch\'emas et des morphismes de sch\'emas (Premi\`ere partie), (Publ. Math. I.H.E.S.}, tome $20$, $1964$).
\bibitem[EGA IV.2]{EGA42} {\sc A. Grothendieck} et {\sc J. Dieudonn\'e}, \emph{\'El\'ements de g\'eom\'etrie alg\'ebrique, IV.2. \'Etude locale des sch\'emas et des morphismes de sch\'emas (Seconde partie), (Publ. Math. I.H.E.S.}, tome $20$, $1964$).
\bibitem[EGA IV.3]{EGA43} {\sc A. Grothendieck} et {\sc J. Dieudonn\'e}, \emph{\'El\'ements de g\'eom\'etrie alg\'ebrique, IV.3. \'Etude locale des sch\'emas et des morphismes de sch\'emas (Troisi\`eme partie), (Publ. Math. I.H.E.S.}, tome $28$, $1966$).
\bibitem[EGA IV.4]{EGA44} {\sc A. Grothendieck} et {\sc J. Dieudonn\'e}, \emph{\'El\'ements de g\'eom\'etrie alg\'ebrique, IV.4. \'Etude locale des sch\'emas et des morphismes de sch\'emas (Quatri\`eme partie), (Publ. Math. I.H.E.S.}, tome $32$, $1967$).
\bibitem[1]{1}{Some less important reference}
\end{thebibliography}
whose output looks like this :

The group of "EGA" references (that is, all references except the last one) is the list of references that I want to keep in this order (labels appear to be already sorted in alphabetical order, but it could not be the case) and always on top of my bibliography.
biblatexis the newest guy in town, and does everything all the multiple bib-specific packages can do with (almost) the blink of an eye. You can define specific rules for sorting and give additionalpresortorsorttitlefields if you want something special. – Johannes_B Mar 10 '15 at 22:14biblatexdocumentation, § 3.6.7, ‘Bibliography categories’,p. 79 and § 3.11.4, ‘Subdivided bibliographies’, p.109–111. – Bernard Mar 10 '15 at 23:41biblatex: it's the actual formatting of the output of (all) the entry types that is tricky. With only one entry type shown, this question is impossible to answer properly. – jon Mar 11 '15 at 00:15\scwas deprecated when LaTeX 2.09 retired to a well-deserved home for elderly formats 20+ years ago.\scshapeor\textsc{}should be used for all LaTeX 2e documents. – cfr Mar 11 '15 at 02:34