Sefaria: a Living Library of Jewish Texts Online
Sefaria.org is a wonderful website that makes finding the sources that a particular text cites easier than should be legal. Click on the footnote of each law of the Mishneh Torah and your gemara/Talmud citation is right there, and you can open it with another click. Back when I was a rabbinical student and in the early days of my rabbinate, we had to use, like, reference skills. It was terrible.