# Relationship history for MSHA mine 3607903

Current hierarchy: **Drebitko Andrew → Bucket Coal Company → Heather Mine**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Zukowski Joseph-James O'Brien Et Al → Heather Mine; 1982-06-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** J & Z Coal Company → Heather Mine; 1987-07-01 to 1988-02-18; source msha-controller-operator-history
- **controller_controls_operator:** Zukowski Joseph-James O'Brien Et Al → J & Z Coal Company; 1987-07-01 to 1988-02-18; source msha-controller-operator-history
- **operator_operates_mine:** Bucket Coal Company → Heather Mine; 1988-02-19 to 1990-07-01; source msha-controller-operator-history
- **controller_controls_mine:** Witmer Kenneth Et Al → Heather Mine; 1988-02-19 to 1990-07-01; source msha-controller-operator-history
- **controller_controls_operator:** Witmer Kenneth Et Al → Bucket Coal Company; 1988-02-19 to 1990-07-01; source msha-controller-operator-history
- **operator_operates_mine:** Bucket Coal Company → Heather Mine; 1990-07-02 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Drebitko Andrew → Heather Mine; 1990-07-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Drebitko Andrew → Bucket Coal Company; 1990-07-02 to current/open; source msha-controller-operator-history