Which tool did Miro Samek use to create UML state diagrams in his C/C++ book

I’m reading through Miro Samek’s book about implementing UML state machines in C and C++ programming. The state diagrams in this book look really clean and professional. I’ve been trying to figure out what drawing tool or software he used to create these diagrams. Does anyone know which program was used for making the statechart illustrations? I want to create similar looking diagrams for my own project documentation. The diagrams have a very specific style and formatting that I’d like to replicate. I’ve tried searching online but haven’t found any information about the specific software package used. Any help would be appreciated.

hey, i think he used Visio for those diagrams! they really do have that nice clean vibe. def worth checking out for ur project! good luck!