Four of the five volumes of the Latin Selectarum Disputationum may be downloaded for free. If you know Latin, Voetius is the best undiscovered Reformed author in the world. It is a fascimile, but still quite readable, and easier by far than, say, Caryl's sermons on Job.
1. Go to
http://gallica.bnf.fr/
2. Click on recherche.
3. Under Mots du titre, type in "disputationum."
4. Under the fourth result, click on "consulter la notice"
5. Click on pars 1.
6. Click on telecharger
7. Click on "ok" at the bottom of the screen
8. After the document is ready, there will be a clickable phrase "en cliquant ici" in blue in the middle of the page. *Right-click* on that phrase, and "save target as" whatever and wherever you want to save it. Repeat instructions 5-8 for the other parts. (go back from the pop-up window to do so).