Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Series # | Production Code | Title | Directed by | Written by | United States Original Airdate | Canada Original Airdate |
| --- | --- | --- | --- | --- | --- | --- |
| 27.0 | 201.0 | "Zipper the Zoomit Dog" | Jos Humphrey | Mark Drop | June 2, 2012 | September 7, 2012 |
| 28.0 | 202.0 | "The Fraud Princess" | Greg Sullivan | Rachel Lipman | June 9, 2012 | September 14, 2012 |
| 29.0 | 203.0 | "The Super Secret Pup Club" | Jos Humphrey | Bart Jennett | June 16, 2012 | September 21, 2012 |
| 30.0 | 204.0 | "Barlow" | Greg Sullivan | Alan Hanson | June 23, 2012 | September 28, 2012 |
| 31.0 | 205.0 | "There's Something About Camelia" | Jos Humphrey | Tony Infante | June 30, 2012 | October 5, 2012 |
| 32.0 | 206.0 | "Good Dog, McLeish!" | Greg Sullivan | Evan Gore | July 7, 2012 | October 12, 2012 |
| 33.0 | 208.0 | "The Ruff Ruff Bunch" | Jos Humphrey | Rich Fogel | July 14, 2012 | October 19, 2012 |
| 34.0 | 209.0 | "Salty" | Greg Sullivan | Merriwether Williams | July 21, 2012 | October 26, 2012 |
| 35.0 | 207.0 | "Squawk" | Greg Sullivan | Chelsea Meyer | July 28, 2012 | November 2, 2012 |
| 36.0 | 212.0 | "The Accidental Pup Star" | Jos Humphrey | Tony Infante | August 25, 2012 | November 9, 2012 |
| 37.0 | 210.0 | "No Dogs Allowed" | Jos Humphrey | Rich Whitley | September 1, 2012 | November 16, 2012 |
| 38.0 | 211.0 | "Pound Preemies" | Jos Humphrey | Eric Trueheart | December 1, 2012 | September 18, 2012 |
Question:
Who were the writers of the episodes directed by Greg Sullivan and which first aired on July 21, 2012?
Answer:
Merriwether Williams