8  Acknowledgements

Grateful acknowledgement is made to the following sources:

Figure 1: deepadesigns/shutterstock.com

Figure 2: © Rawpixel.com/Shutterstock

Figure 3: Publisher unknown.

Figure 4: From Pixabay. Covered under Creative Commons licence CC0 1.0 Universal (CC0 1.0) Public Domain Dedication

Figure 5: Examples of Google, Bing and Yahoo! Search

Figure 6: From Pixabay. Covered under Creative Commons licence CC0 1.0 Universal (CC0 1.0) Public Domain Dedication

Every effort has been made to contact copyright holders. If any have been inadvertently overlooked the publishers will be pleased to make the necessary arrangements at the first opportunity.