George Dinwiddie proposes a list of material that should help you in the task of splitting user stories used to manage requirements in Agile approaches. In his own handout, he explains the difference between stories in the backlog that are often called features or epics and stories selected for development that should generally be small enough to be done in a matter of hours to a couple of days at the most.
How to Split User Stories
Resources
Strategic & Reactionary User Research
User research is often initiated during a Scrum sprint, after a design is implemented, or is part of the MVP. But, mindfully planning research earlier reaps far better results.
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Resources
Use Cases Definition by Usability.gov
Usability.gov is the primary government source for information on usability and user-centered design. The web site has a page dedicated to use cases that explains what they are and how to use them.
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Resources
UML Unified Modeling Language Tools Directory
This website presents a list of Unified Modeling Language (UML) tools
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