| year of publication | ISBN | author(s) | title |
|---|---|---|---|
| 2004 | 978-1-900013-22-2 | C Johnstone · M Bowra | Guide to Tightness Testing and Purging Small Natural Gas Installations |
| 2000 | 978-1-900013-89-5 | Michael Bowra · Chris Johnstone | Domestic Central Heating Training Pack |
| '' | 978-1-900013-99-4 | Michael Bowra · Chris Johnstone | Domestic Natural Gas Handbook (Including Appliances) |