For studying náhuatlisms—the incorporation of Nahuatl words into Spanish—key resources include dictionaries of aztequismos, linguistic studies by Mexican scholars, and contemporary research from UNAM and the Academia Mexicana de la Lengua.
Essential Dictionaries and Reference Works
Diccionario de aztequismos, Cecilio Robelo (1904) – One of the first systematic dictionaries documenting over 2,000 Nahuatl-derived Spanish words, including toponyms, demonyms, and words of common use
Diccionario del náhuatl en el español de México, Carlos Montemayor (2007) – A comprehensive modern study of Nahuatl words and their adaptation in Mexican Spanish
An Analytical Dictionary of Nahuatl, Frances E. Karttunen (1983) – A detailed resource for the linguistic features, meaning, and etymology of Nahuatl words
Nahuatlismos en el español de México, Svetlana Iakovleva (2021) – Focuses on phonetic, morphological, and semantic adaptation of Nahuatl words in Mexican Spanish

Scholarly Works on Linguistic and Cultural ContextElena García Frazier, Préstamos del náhuatl al español mexicano (Hesperia: Anuario de filología hispánica, 2006) – Discusses phonetic changes and semantic evolution of Nahuatl-derived words
José G. Moreno de Alba, El español de América (1988) – Includes studies on Nahuatl influence in regionally spoken Mexican Spanish
Silvio Zavala, El español, ¿lengua obligatoria? (1995) – Explores historical language policy and the diffusion of Nahuatl words
UNAM Publication: Nahuatlismos en el español de México (Iakovleva, 2021) – Provides detailed categorization, diachronic and synchronic analysis, and tables of lexical usage

Online and Digital Resources
Academia Mexicana de la Lengua: Nahuatlismos de referente – Offers examples of Nahuatl words with references to contemporary usage
Nahuatlahto: vida e historia de un nahuatlismo – Research article detailing the life and history of specific nah u at lists
Wikipedia / Wikiwand: Nahuatlismo – Provides bibliographies and background studies for exploration