# Theory of Constraints for Service Businesses — Resources

## Knowledge

- [IT-Premium Value Streams & Flow Constraints](https://writebook.it-expert.com.ua/8/business/82/it-premium-value-streams-flow-constraints)
  Primary course case, refreshed 19 July 2026. Use for: Level 0/1 value-stream maps, `Абонплата` recurring-income attribution, time-log capacity mix, RFC phase queues, cash context, scorecard design, and the four-week experiment.
- [Goldratt Research Labs: Introduction to Theory of Constraints](https://www.goldrattresearchlabs.com/introduction-to-toc)
  Concise statement of the Five Focusing Steps and the role of Throughput Accounting and Thinking Processes. Use for: canonical TOC sequence and terminology.
- [Goldratt Research Labs: “What is Theory of Constraints?”](https://www.goldrattresearchlabs.com/pdf/What_is_Theory_of_Constraints_%28TOC%29.PDF)
  Downloadable overview explaining application of the focusing steps across functions and organizations. Use for: defining the system, goal, necessary conditions, measurements, and constraint.
- [North River Press: Goldratt titles](https://northriverpress.com/)
  Publisher of Goldratt's core books. Use for: choosing primary readings, especially _The Goal_, _Critical Chain_, and _Goldratt's Rules of Flow_.
- Eliyahu M. Goldratt and Jeff Cox, _The Goal: A Process of Ongoing Improvement_ (North River Press).
  Foundational narrative treatment. Use for: intuition about flow, dependent events, statistical fluctuations, constraint exploitation, and local efficiency traps.
- Efrat Goldratt-Ashlag, _Goldratt's Rules of Flow_ (North River Press).
  Project-flow treatment explicitly aimed at engineering, IT, service, and sales. Use for: project WIP, lead time, due-date reliability, and obstacles to flow.

## Wisdom (Communities)

- [TOCICO — Theory of Constraints International Certification Organization](https://www.tocico.org/)
  Practitioner and certification community. Use for: implementation cases, terminology checks, conferences, and critique from experienced TOC practitioners.

## Gaps

- Validate the live IT-Premium constraint with weekly phase-age and transition data; a one-day snapshot proves queue location, not causality.
- Normalize `Абонплата` postings to contracted monthly value before treating the accounting series as MRR; prepaid, catch-up, and non-monthly postings can distort a single month.
- Add phase-transition timestamps so elapsed lead time and wait time can be separated from the newly available time-log touch-time data.
- Add a high-trust service-specific source on throughput accounting when the course reaches pricing and work-selection decisions.