1 Subjects: “...back pain...”

2 Subjects: “...back-propagation neural network...”

3 Subjects: “...build back better...”

4 Subjects: “...feed-back processes...”

5 Subjects: “...back-extraction...”

6 Subjects: “...back calculation of modulus...”

7 Subjects: “...back-propagation neural network...”

8 Subjects: “...die-back of poplars...”