On equivalence of multi-letter and multi-letter measure-many quantum finite automata

Hierarchy and equivalence of multi-letter quantum finite automata

Multi-letter quantum finite automata: decidability of the equivalence and minimization of states

Multi-letter Reversible and Quantum Finite Automata

Another approach to the equivalence of measure-many one-way quantum finite automata and its application

Another approach of the equivalence problem for measure-many one-way quantum finite automata

Determining the equivalence for one-way quantum finite automata