Crossword puzzle clue "four groups found in this puzzle"

Four groups found in this puzzle

Impersonal notes ... or what four groups of this puzzle's answers do (totaling 11 words)

Skeletal parts, four of which can be found in rows four, seven, nine, and twelve

Secret's source ... that can be found four times in this puzzle

Exhibit found in this puzzle's four longest answers

Main thoroughfare in Manhattan (one can be found in each of the four long answers in this puzzle)

Trellis flower, and something found four times in this puzzle

Easy-to-park vehicles ... or what can be found four times in this puzzle