To find a list of files in the current directory (including subdirectories) that contain certain strings, use this 

> rgrep -l -R '*.scm' SayPhones .

will (l)ist the filenames (among .scm files) containing the string "SayPhones" recursively in the current directory.

To replace a letter with a "return key" in a query-replace in Emacs:

> ESC-%
> type a letter to be replace with
> CTRL-Q, CTRL-J (Ctrl-Q for "take this literally", and Ctrl-J for "return key")