Drawings are licensed under the Creative Commons Licence (CC-BY-NC-SA 4.0 DEED). You are welcome to use my pictures under these conditions. Please indicate as source: Martin Schlobach – buildingservicestutor.com. If you have any questions, please send me an e-mail.
Images and illustrations that are not mine or originate from another source are labelled with a source note.
Greetings Martin