First things first: you're looking for literary criticism within journals, not book reviews. A work of literary criticism differs from a book review in that it is typically a more in-depth critique of a work, and it's most often intended for an academic audience.
To find literary criticism, search keywords like the title of the work, author's name, and themes.
Answer: Databases! (You will not find journal articles on Google, sad to say...)
Try a Keyword search in the Catalog with the author's name.
Tip: An author search for an author's name will bring up books by the author, not about him or her. Use the author's name and criticism or interpretation to find results. For example: Nabokov, Vladimir and criticism.
A Subject search can be done with the author's last name, and first name (Nabokov, Vladimir). Then look for subheadings criticism and interpretation.
You might also check to see if a bibliography has been published on the author you're researching. To search the catalog for these, try the author's name and "bibliography" as a keyword search. Example: nabokov bibliography