In the fourth installment of a blog series on Zephyr Archaeotech Emporium's use of Pulumi, the focus is on employing Stack References to link different projects and enhance infrastructure management. Zephyr, a fictional company, has structured its Pulumi projects into three distinct parts—zephyr-infra for base infrastructure, zephyr-k8s for the Kubernetes platform, and zephyr-app for deploying online store services. This structure supports multiple teams and allows the application to evolve separately from its supporting infrastructure. The blog elaborates on Stack References, a method allowing different stacks to share information, addressing cross-project dependencies without hard-coding values. Best practices include exporting only necessary stack outputs, minimizing the use of stack references to reduce project coupling, and parameterizing stack references to avoid hardcoding. The blog also highlights the importance of planning for cascading stack updates and keeping security considerations in mind. The series aims to gradually expose best practices in infrastructure as code (IaC) management, and the next post will address security and role-based access control (RBAC).