Is comma, semicolon or full stop is needed in these sentences? If it is, when and which of these punctuations?
Furthermore, I really appreciate if you name the grammatical name of the first part of each of the following sentences. To be more precise "to find a book on a certain subject" and "to find a magazine article on a subject".
To find a book on a certain subject you used to look in a card catalog.
To find a magazine article on a subject you used to look in a periodical index.