The Croatian work pictured at left, Latinska historička gramatika (Latin Historical Grammar) was composed by Anton Mayer and published in 1939 in Zagreb by the Kluba Studenata Klasične Filologije. It is made up of two fasicles, the first on nominal and verbal forms, the second on consonantism. There doesn't seem ever to have been a third fascicle on vocalism. Mayer is best known in Latin circles for his (unsuccessful) article, Die Entstehung des lateinischen Perfektsystems. Glotta 32:261-82, but he also wrote a well known work on Illyrian, Die Sprache der alten Illyrier, in 1957 and 1959, the heyday of Illyromania.
The work in question is a pretty barebones, only about 90 large typescript pages, few citations, no bibliography, but it has some nice observations in it, and is definitely the work of a IE-ist more than a Latin linguist. For example, the Latin imperfect is analyzed as a nominal case form plus an ā-preterite of *bhuhx- and compared to the Slavic imperfect (p. 16, correctly in my view), the length of ēst 'eats' is explained by Lachmann's Law (p. 36, probable). For Croatian-readers this book has been replaced by the excellent Matasović 1997. Yale and UBC have copies of this book.