With everything that is floating around in popular culture regarding these two figures it becomes, if not hard, then at the very least tedious to sort through the falsehoods and sensationalism to find out the empirical truth. It becomes even more difficult when the figure belongs to a different language sphere. Basically, my question is, what are some good, scholarly, reputable English language sources on Vlad Tepes and Elizabeth Bathory? Preferably something peer-reviewed or at leased published by a trustworthy scholar. I'd like to know if Vlad and Elizabeth were really as terrible as they were reported to be or whether they were much more complex and nuanced than previously thought. Thank you.
Since you're interested in the complexity and nuance of Báthory's story, I can recommend my very long AH biography & analysis of Báthory's case, a shorter piece on why Báthory was definitely not innocent, or my answer to the question "why wasn't Báthory caught sooner?"
I can also help you with sources. I will list them below on a “traffic light” scale: green means go, yellow means be careful, red means stop.
“Green light:” well-researched, credible, readable sources
Bledsaw, Rachel L. No Blood in the Water: The Legal and Gender Conspiracies Against Countess Elizabeth Báthory in Historical Context in “Theses and Dissertations 135,” Illinois State University, 2014.
Craft, Kimberly L. The Private Letters of Countess Erzsebet Báthory. CreateSpace Independent Publishing Platform (self-published), 2011.
Kord, Susanne. “Chapter 3: Bloodbaths: the case of Elizabeth Báthory” in Murderesses in German Writing 1720-1860: Heroines of Horror. Cambridge University Press, 2009.
Miller, Elizabeth. “Bram Stoker, Elizabeth Báthory and Dracula” in Dracula – Sense and Nonsense. Desert Island Books, 2006.
Thorne, Tony. Countess Dracula: The Life and Times of Elisabeth Báthory, the Blood Countess. Bloomsbury Pub Ltd., 1997.
“Yellow light:” somewhat useful, somewhat flawed sources
Craft, Kimberly L. Infamous Lady: The True Story of Countess Erzsebet Báthory. 2nd ed., CreateSpace Independent Publishing Platform (self-published), 2014.
“Red light:” pseudo-history, pseudoscience, conjecture, misinformation
These sources are very interesting from a historiographical perspective (historiography is the history of how people wrote about a subject, in this case Elisabeth Báthory), but they are not useful for a factual understanding of Báthory's life or crimes.
Baring-Gould, Sabine. The Book of Were-Wolves: Being an Account of Terrible Superstition. Smith, Elder, & Co., 1865. See pages 138-139.
McNally, Raymond. Dracula Was A Woman: In Search of the Blood Countess of Transylvania. McGraw-Hill, 1987.
Paget, John. Hungary and Transylvania: With Remarks on Their Condition, Social, Political, and Economical. 1839, pp. 68-69.
Penrose, Valentine. La Comtesse Sanglante : Erzsebet Báthory. Gallimard, 1984. In French. Translated into English as The Bloody Countess: Atrocities of Erzsebet Báthory. Translated by Alexander Trocchi, 2nd ed., Sun Vision Press, 2012.
von Elsberg, R. A. Elisabeth Báthory. (Die Blutgräfin) Ein sitten-und charakterbild. S. Schottlaender Breslau, 1904. In German; no English translation available.