^(?:\b[A-Z]{1}[a-z]*\b\s?)+$
^                               // Start of string
 (?:                     )+     // Capture the following group one or more times
    \b                          // Word boundary
      [A-Z]{1}                  // Exactly one upper case letter
              [a-z]*            // Zero or more lower case letters
                    \b          // Word boundary
                      \s?       // Zero or one white space character
                           $    // End of string

Try it here