How to cite the "EFDC+ theory document"?

I want to cite the “THE ENVIRONMENTAL FLUID DYNAMICS CODE:THEORETICAL & COMPUTATIONAL ASPECTS OF EFDC+ (2017)” in the paper. However, because this article cannot be retrieved in Google Scholar, which I used to generate the reference format, I failed to generate it. Can someone tell me the correct reference format for this document?

Thank you for your question. Please use the following citations:DSI, 2017. The Environmental Fluid Dynamics Code: Theoretical & Computational Aspects of EFDC+, Dynamic Solutions - International, LLC, Edmonds, WA, USA, 2017. Craig, Paul M. 2016. User’s Manual For EFDC_Explorer Modeling System: A Pre/Post Processor for the Environmental Fluid Dynamics Code, Dynamic Solutions - International, LLC, Edmonds, WA, USA, March, 2016.

Please now cite this document as follows:DSI, 2020. EFDC+ Theory, DSI, LLC, Edmonds, WA, USA, 2020. Available at EFDC+ Theory Guide – EE Modeling System Accessed on YYYY-MM-DD