Rob writes,

Listening to you on the Heidelblog/Heidelcast and Office Hours, you have given me a enormous desire to read more “classic reformed theology.” I am currently reading Turretin’s Institutes and I would love to know who are some more classic reformed theologians and pastors I can read? I’ve gathered from listening to you that I should read Olevanius, Vitringa (if I can find anything in English….), Gisbertus Voetius, and Franciscus Junius.

If you have time, would you be willing to point me in the direction of others? Thank you so much for your work in the gospel, specifically as it is articulated confessionally in the reformed tradition!

Grace and peace,

Rob

Thank you Rob for the encouragement.

Your reading list looks very good right now but here are 36 suggestions in rough chronological order:

1. Heinrich Bullinger, Decades. This large collection of sermons represents a turning point in early Zürich theology. They were widely read in the English world too and well appreciated.
2. John Calvin, Institutes of the Christian Religion. The Battles edition is the modern critical edition (with footnotes and textual apparatus etc. There is much to commend it but the Beveridge edition is widely available and inexpensive (or free) because it is in the public domain. Some scholars prefer the Allen translation from earlier in the 19th century for its fidelity to the way the Institutes originally appeared.
3. Petrus Dathenus, The Pearl of Christian Comfort, trans. A. Blok (Grand Rapids: Reformation Heritage Books, 1997). An excellent example of the confessional Reformed piety of the late 16th and early 17th centuries.
4. Theodore Beza, The Christian Faith, trans. James Clark (Lewes: Focus Christian Ministries Trust, 1992).This is Beza as he actually was. Needless to say, this is not the Beza of most of the secondary texts. See also Beza’s A Clear and Simple Treatise on the Lord’s Supper.
5. Peter Martyr Vermigli, Predestination and Justification: Two Theological Loci, trans. Frank James (Kirksville, MO: Truman State University Press, 2003). Several of Vermigli’s works have been translated into English in the last two decades. He was a Roman theologian who taught in Lucca and who led a number of other Italian Romanists to the Reformation before fleeing to Zürich and Cambridge. He was influential and well regarded in the classical period of Reformed theology.
6. Caspar Olevianus, A Firm Foundation, trans. Lyle D. Bierma, (Grand Rapids: Baker, 1995). An edifying introduction to classic Reformed covenant/federal theology written by one of the chief contributors to the Heidelberg Catechism. Written in catechetical format, Lyle Bierma, the translator and editor, has correlated it to the Heidelberg Catechism. This is an excellent resource for those catechetical sermons or membership classes. See also Olevianus’ An Exposition of the Apostles’ Creed, trans. Lyle Bierma (Grand Rapids: Reformation Heritage Books, 2010). The second volume in the Classic Reformed Theology series, this is a good introduction to the Reformed doctrines of covenant and kingdom and to the catholic faith summarized in the creed.
7. Girolamo Zanchi, Confession of the Christian Religion (De religione christiana fides), trans. Luca Baschera and Christian Moser. Studies in the History of the Christian Tradition  (Leiden/Boston: Brill, 2007). Along with Vermigli,  Zanchi was a convert from Romanism to the Reformed confession. He was well regarded and widely read.
8. Zacharias Ursinus, Commentary on the Heidelberg Catechism. There is more Reformed theology than Calvin and his Institutes, however. Ursinus was the principal author of the Heidelberg Catechism (1563) and its authorized commentator. This 19th-century English translation is imperfect (we’re working on it) but this work is invaluable.
9. Robert Rollock, A Treatise of God’s Effectual Calling in Select Works of Robert Rollock. He was a significant transitional figure in the late 16th century. He mediated Palatinate theology to Scotland and influenced the Westminster Divines.
10. Franciscus Junius, On True Theology, trans. David C. Noe (Grand Rapids: Reformation Heritage Books, 2014). This is one of the more important volumes in this list. It is essential reading. Much of the volume is actually Junius’ biography. The treatise itself is not very long but it is very important. Junius is clear and reasonably easy to read. This is a primary source for what I call the categorical distinction (the Creator/creature distinction) as applied to Christian theology.
11. William Perkins, Commentary on Galatians. See also his Golden Chain, which has been reissued in recent years. Perkins will not disappoint and you will learn something from every page and you will be edified.
12. Synopsis of a Purer Theology. So far there are two volumes (1, 2) available in English. The Synopsis records the attempt by confessional Reformed theologians and students, in the Netherlands, to re-establish Reformed orthodoxy in the wake of the Remonstrant controversy after the Synod of Dort. These volumes are very expensive, however. You might want to find them in a library or via the Inter-Library Loan system. They are not easy going but they are enlightening about the state of Reformed theology in the early 17th century.
13. Johannes Wollebius, Compendium of Christian Theology in J. W. Beardslee, ed. and trans., Reformed Dogmatics (New York: Oxford University Press, 1965), 29–190. You may be able to find Beardslee’s Reformed Dogmatics used or via inter-library loan. It is worth the hunt. The Compendium is a concise, edifying survey of the faith.
14. William Ames, Marrow of Theology. This volume is readily available and a very clear presentation of early 17th-century Reformed theology. Ames is particularly important as a student of Perkins and the principal mediator of English Reformed theology to the Netherlands (and later to the New World). See also his Sketch of the Christian’s Catechism. These were Ames’ sermons guided by the Heidelberg Catechism.
15. Edward Fisher, The Marrow of Modern Divinity. This volume is something of a litmus test. It was criticized by neonomians when it was first published but it was staunchly defended by orthodox men (e.g., Thomas Boston, who republished it in the 18th century). This is a challenging but eminently worthwhile book.
16. Gisbertus Voetius, Select Theological Disputations in J. W. Beardslee, ed. and trans. Reformed Dogmatics (New York: Oxford University Press, 1965), 262–334. See also the translation of his treatise on Spiritual Desertion. There is little of Voetius in English but more is on the way.
17. George Gillespie, A Dispute Against The English Popish Ceremonies. rev. ed. (Dallas: Naptali Press, 2013). This along with Ames’ Fresh Suit is perhaps the most important 17th-century articulation and application of the Reformed rule of faith (i.e., the regulative principle).
18. Samuel Rutherford, The Covenant of Life Opened or A Treatise of the Covenant of Life. He was a major figure in 17th-century Reformed theology. You might also take a look at his Letters to see his pastoral piety. This is an important work in the history of Reformed covenant theology.
19. John Owen, The Doctrine of Justification By Faih in The Works of John Owen, vol. 5. ed. W. H. Goold (New York, 1841). Owen may have been the greatest theologian in the English-speaking world in the 17th century. Owens works are extensive, including a major commentary on the book of Hebrews. I selected this volume because it represents his work well and addresses a crucial issue. You will also want to take a look at his, Death of Death in the Death of Christ. 
20. Francis Turretin, Institutes of Elenctic Theology, 3 vols. trans. G. M. Giger, ed. J. T. Dennison (Phlipsburg: P&R, 1992-1997). One of the greatest of the 17th-century Reformed dogmatic works, it has retained its influence through its use at old Princeton. These volumes put in your hands an excellent representative of high Reformed orthodoxy and polemical theology
21. Johannes Cocceius, Doctrine of the Covenant and Testament of God. This work appeared in English last year for the very first time. It was controversial but important.
22. Herman Witsius, Economy of the Covenants. These volumes are widely available and essential reading. This is an edifying work from which you will learn a great deal. His commentary on the Apostles’ Creed and his commentary on the Lord’s Prayer are also available and worth having and reading.
23. Wilhelmus a Brakel, The Christian’s Reasonable Service, 4 vol. trans. Bartel Elshout (Ligioner: Soli Deo Gloria, 1992). 
24. P. Van Mastricht, A Treatise on Regeneration (Soli Deo Gloria, repr. 2002). There is little of Mastricht in English (though more is on the way). He influenced Edwards. Under every head of doctrine he considered exegetical theology, historical theology, systematic theology, and pastoral theology. See also the translation of The Best Method of Preaching.
25. Thomas Boston, A View of the Covenant of Grace (reprint edition; Lewis, UK: Focus Christian Ministries Trust, 1990)
26. Bernardinus de Moor, Continuous Commentary on Johannes Marckius’ Didactico-Elenctic Compendium of Christian Theology (Commentarius Perpetuus in Johannes Marckii Compendium Theologiae Christianae Didactico-Elenchticum [1761- 1772]).  This work gives us a good idea of the state of Reformed theology in the 18th century as well as a glimpse into the work of Johannes a Marck, from the 17th century.

Doubtless there are other volumes to be added to this list. It is a much more complete list than was possible even 10 years ago and should keep one busy for a few years. The list is weighted a bit toward the late 16th and early 17th centuries but it gives you a reasonable representation from across Europe and the British Isles and covers Reformed theology from the mid-16th century into the 18th century. You asked about Campegius Vitringa. There is little of his work in English beyond, The Synagogue and the Church, translated and condensed by Joshua L. Bernard (London, 1842). This is more a paraphrase than translation but useful for getting a sense of how Vitringa worked.