APA (7th ed.) Citation

Hugo's Language Institute. (1900). Key to the "Standard" edition of Spanish grammar simplified. Hugo's Language Institute.

Chicago Style (17th ed.) Citation

Hugo's Language Institute. Key to the "Standard" Edition of Spanish Grammar Simplified. London: Hugo's Language Institute, 1900.

MLA (9th ed.) Citation

Hugo's Language Institute. Key to the "Standard" Edition of Spanish Grammar Simplified. Hugo's Language Institute, 1900.