# 561 Group Shop

> Books from the 561 Group, as EPUB and PDF. Every edition is proofread independently, and each book's page gives the digests of the exact files you receive. The Shop is the storefront for people of Causeway Services, part of the 561 Group: books to buy and read, a library per reader, and gifts.

shop.561.group is inside bazaar.561.group, which is inside market.561.group. People buy here; software that pays per request uses the Market.

## Books

- [Understanding Infection-Associated Chronic Illness](https://shop.561.group/goods/understanding-infection-associated-chronic-illness): A public guide to Long COVID, post-exertional malaise, and infection-associated chronic illness: what is established, what is a well-support
- [The Agent Operator's Handbook](https://shop.561.group/goods/the-agent-operators-handbook): A field guide to operating several AI coding agents at once: writing the complete brief, when to split work and when not to, steering a runn
- [The x402 Economy](https://shop.561.group/goods/the-x402-economy): How the web’s unused payment code became a way for software to pay, and what it has earned so far: HTTP 402’s history, one paid request step
- [Project Management, Course by Course](https://shop.561.group/goods/project-management-course-by-course): A study companion to Google’s Project Management Certificate: one chapter per course, self-checks with answers, and a guide to the capstone.
- [Project Management Fundamentals, Domain by Domain](https://shop.561.group/goods/the-capm-domain-by-domain): A study companion to PMI’s CAPM exam that follows the 2023 outline task by task and ends with a 40-question practice exam. Independent of PM
- [Data Analytics, Course by Course](https://shop.561.group/goods/data-analytics-course-by-course): A study companion to Google’s Data Analytics Certificate: spreadsheets, SQL, Tableau and Python, with tested code and answered self-checks. 
- [UX Design, Course by Course](https://shop.561.group/goods/ux-design-course-by-course): A study companion to Google’s UX Design Certificate: the design process from its sources, accessibility throughout, and a portfolio guide. I
- [Business Management, Course by Course](https://shop.561.group/goods/business-management-course-by-course): A study companion to Cornell’s Business Management Essentials certificate: finance, marketing, strategy, organizing and leading. Independent
- [Business Strategy, Course by Course](https://shop.561.group/goods/business-strategy-course-by-course): A study companion to Cornell’s Business Strategy certificate: value, disruption, alliances, game theory and platforms. Independent of Cornel
- [The Whirling Crystal](https://shop.561.group/goods/the-whirling-crystal): A working account of a live mathematics program, tracing a path from Fregean predicate application through Belnap’s FOUR, Chu spaces and Hoa
- [The Second Day](https://shop.561.group/goods/health-education-newsletter): A health-synthesis newsletter about infection-associated chronic illness. No subscription is open yet.
- [Ice Out](https://shop.561.group/goods/ice-out): June Tam comes home to Duluth for one winter to help run her family's Cantonese restaurant after her father's stroke. Anders Holm, who washe
- [561 Group merch](https://shop.561.group/goods/merch): Print-on-demand goods. Not open yet.

## Machine interfaces

- [Shop catalog JSON](https://shop.561.group/catalog.json): every offering with prices and edition digests (GET)
- [Shop MCP](https://shop.561.group/mcp): POST JSON-RPC with list_products, search_products and get_product
- [Bazaar discovery](https://bazaar.561.group/discovery.json): compare the Shop's books with the Market's services
- [Market x402 services](https://market.561.group/x402/): how software pays per request over HTTP 402

## Optional

- [561 Group Bazaar](https://bazaar.561.group/)
- [561 Group Market](https://market.561.group/)
- [Causeway Services](https://services.561.group/)
- [561 Group](https://561.group/)