Mr. Costa joined the old Biblioteca Nacional Vasco da Gama (presently the Central Library) in 1930. He became the curator in 1949 and retired in 1967. During his tenure of nearly four decades, Mr. Costa made an impressive collection of some eleven thousand publications by Goans, written in fourteen languages and spanning practically the entire Portuguese era.

In addition, he also compiled the bibliographical and biographical data of over 2000 Goan writers, representing the period 1702 through 1961. This major compilation, Dicionário da Literatura Goesa, was published in 1971 by Fundacao Oriente, Lisbon, and has been acclaimed as "a wonderful bibliographic repository for those who would like to undertake a study of the political, social, economic and religious life of Goa's distant past".

 

Mr. Costa's Dicionário da Literatura Goesa, also includes biographical data on 200 Goans who wrote in Marathi and Sanskrit, the notable among these being the novelists Ramchandra Bicaji Gunjikar and Suriaji Mahatame.