1985 a. "New Light on the Identity of "Geber"." Sudhoffs Archiv, 69, (1985), pp. 76-90.

        1985 b. "The Genesis of the Summa perfectionis." Archives internationales d'histoire
                  des sciences, 35, (1985), pp. 240-302.
 
        1989. "Technology and Alchemical Debate in the Late Middle Ages." Isis, 80, (1989),
                  pp. 423-445.

        1991. The Summa perfectionis of Pseudo-Geber. Brill, Leiden.
 
        1993 a. "The Corpuscular Theory of J. B. Van Helmont and its Medieval Sources."
                  Vivarium, 31,  (1993), pp. 161-191.
 
        1993 b. "L'influence de la Summa perfectionis du pseudo-Geber." in J.-C.Marglin &
                  S.Matton (eds.), Alchimie et philosophie a la Renaissance. Paris, 1993. pp. 65-77.
 
        1994 a. "The Corpuscular Transmutational Theory of Eirenaeus Philalethes." in
                  P. Rattansi et A. Clericuzio (eds. ), Alchemy and Chemistry in the 16th and 17th
                  Centuries. Dordrecht, 1994. pp. 161-182.
 
        1994 b. Gehennical Fire : The Lives of George Starkey, an American Alchemist in
                  the Scientific Revolution. Harvard U. P.

        1994 c. "Boyle's Debt to Corpuscular Alchemy." in M. Hunter (ed. ), Robert Boyle
                  Reconsidered. Cambridge, 1994. pp. 107-118.

        1994 d. "The Alchemy of Roger Bacon and the Tres Epistolae attributed to him."
                  in Comprendre et maitriser la Nature au Moyen Age. Geneve, 1994. pp. 461-479.

        1995 a. "George Starkey and the Selling of Secrets." in M. Greengrass et al. (ed. ),
                  Samuel Hartlib and Universal Reformation. Cambridge, 1995. pp. 193-210.
 
        1995 b. "The Philosophers' Egg : Theory and Practice in the Alchemy of Roger
                  Bacon." in Le crisi  dell�falchimia, Micrologus, 3, (1995), pp. 75-101.
 
        1996 a. "The Occult and the Manifest among the Alchemists." in F. J. Ragep et
                  S. P. Ragep (eds. ),  Tradition, Transmission, Transformation : Proceedings of
                  two Conferences on Pre-modern  Science held at the University of Oklahoma.
                  Brill, Leiden, 1996. pp. 173-198.
 
        1996 b. ""Decknamen or pseudochemical language ?" : Eirenaeus Philalethes and
                  Carl Jung." in Theorie et pratique dans la constitution des savoirs alchimiques,
                  Revue d'histoire des  sciences, 49, (1996), pp. 159-188.

        1996 c. "The Alchemical Sources of Robert Boyle's Corpuscular Philosophy."
                  Annals of Science, 53, (1996), pp. 567-585.

        1997. "Art, Nature and Experiment among Some Aristotelian Alchemists." in E. Sylla
                  et M. Mc Vaugh (eds. ), Texts and Contexts in Ancient and Medieval Science.
                  Brill, Leiden. pp. 305-317.

        1998 (with Lawrence M. Principe). "Alchemy vs. Chemistry : The Etymological Origines
                  of a  Historiographic Mistake." Early Science and Medicine, 3, (1998), pp. 32-65.