Help 33...: Tekla Structures 21.1 Sr1 Update With

Released in late 2016, version 21.1 introduced:

This service release focuses on stability and refining modeling workflows: Tekla Structures For Students - Trimble Downloads Tekla Structures 21.1 SR1 Update with Help 33...

Better handling of parametric profiles and plugin descriptions. Help 33 Integration: Released in late 2016, version 21

While there isn't a specific academic "paper" published under that exact title, the Tekla Structures 21.1 Service Release 1 (SR1) Released in late 2016