Suffix Study ια
The use of the suffix ια is interesting to study. According to Buck and Petersen combined words in -ια, Ion. -ιη, and those in -ιӑ in the same list because of practical convenience and their interrelations in Greek. On the other side there are uses that actually have their own peculiarities. There are many substantives without connections with adjectives in -ιος because prehistoric substantivations may be surmised. Καρδίας (in genitive) is an example of old concrete substantives in -ια is related to Hittie gen. kardias. Words in -ιă or -įāreflect a type which in the other IE languages appears as an ī/yā stem such as in Sankrit (nom. devī, acc. devīm, gen. devyās, dat.devyāi, etc.).
 Buck, C.D. and W. Petersen. A Reverse Index of Greek Nouns and Adjectives. Hildesheim: Georg Olms, 1984.
 Emde Boas, Evert van, Albert Rijksbaron, Luuk Huitink, and Mathieu de Bakker. The Cambridge Grammar of Classical Greek. Cambridge: Cambridge University Press. 2019. Hudson-Williams, T. A Short Introduction to the Study of Comparative Grammar (Indo-European). Cardiff: University of Wales Press, 1961.
 Kretschmer, Paul and Ernst Locker. Rückläufiges Wörterbuchder Griechischen Sprache. 3., Unveränderte Aufl. Göttingen: Vandenhoeck und Ruprecht.1977.
 Liddell, H.G., and R. Scott. A Greek-English Lexicon. 9th ed. rev. by H. S. Joneswith a Revised Supplement by P. G. W. Glare. Oxford, 1996.
 Palmer, L.R. The Greek Language. London: Faber & Faber, 1980.
 Sihler, Andrew L. New Comparative Grammar of Greek and Latin. Oxford: Oxford University Press, 1995.
 Smyth, Herbert Weir. Greek Grammar. Harvard, 1920, 1956.