1 Subjects: “...Society’s Urgent Challenges...”

2 Subjects: “...challenges...”

3 Subjects: “...grand challenges...”

4 Subjects: “...grand societal challenges...”

5 Subjects: “...challenges...”

6 Subjects: “...challenges...”

7 Subjects: “...social media and new challenges...”

8 Subjects: “...Main spatial challenges...”

9 Subjects: “...challenges...”

10 Subjects: “...governance challenge...”

11 Subjects: “...challenge trials...”