Final answer:
The transitional expressions 'hence' and 'overall' are used to indicate a summary or conclusion in writing.
Step-by-step explanation:
The transitional expressions that can indicate a summary or conclusion are 'hence' and 'overall'. 'Hence' is often used to indicate a logical conclusion or result of the information presented and 'overall' is used to summarize or give the essence of the discussion prior to the conclusion. On the other hand, 'above' and 'initially' are not generally used to indicate summary or conclusion, while 'specifically' is used for detail and emphasis, not summarizing.