Books on Solace (Pubsub+)

I second that - Solace Training is a one-stop resource for sure. However, the following references within Solace would also come in handy.

On GitHub##

Solace Samples
Solace Labs References
Solace Community References on GitHub
Solace IoT Projects on GitHub
Solace Training - Hands on Labs on GitHub

Some specific references

Solace CLI Reference
Solace Error/Message Details

Portals

Solace Developers
Solace Technical Documentation
Solace API Tutorials
Solace Resources * IMPORRTANT*
Solace Learn * General Reference *
Solace Codelabs * IMPORTANT *
Solace Community

External Resource Repositories

Solace on YouTube
Solace on Twitch
Solace on LinkedIn
Solace on Dev.to
Solace on Twitter

Public Repositories

EDA Summit 2021