Inside your essay, you can’t just say “(Tolstoy 45)” and hope for the best—that would leave your reader guessing which Tolstoy masterpiece you mean. You need to add the title (shortened if needed) to the parenthetical. Like this: (Tolstoy, Anna Karenina 45).
If you mention the title in your sentence, you can drop it from the parentheses. For example: “In War and Peace, Tolstoy argues…” then just (234) at the end. Smooth, efficient, and utterly chic.
A Real-World Example
Let’s say you’re citing two books by bell hooks: All About Love and The Will to Change. Your Works Cited should look like this:
hooks, bell. All About Love: New Visions. William Morrow, 2000.
---. The Will to Change: Men, Masculinity, and Love. Washington Square Press, 2004.
Notice the lower-case “hooks”—bell hooks chose to skip capitalization, so you honor that. Respect the artist’s rules, even in citations. It’s a small flex of literary awareness.