@article{Apelt_1966,
    doi = {10.1002/malq.19660120111},
    url = {https://doi.org/10.1002%2Fmalq.19660120111},
    year = {1966},
    month = {jan},
    publisher = {Wiley},
    volume = {12},
    number = {1},
    pages = {131--168},
    author = {Harry Apelt},
    title = {Axiomatische Untersuchungen über Einige mit der Presburgerschen Arithmetik Verwandte Systeme},
    journal = {Mathematical Logic Quarterly}
}

@article{Apelt_1966, doi = {10.1002/malq.19660120111}, url = {https://doi.org/10.1002%2Fmalq.19660120111}, year = {1966}, month = {jan}, publisher = {Wiley}, volume = {12}, number = {1}, pages = {131--168}, author = {Harry Apelt}, title = {Axiomatische Untersuchungen über Einige mit der Presburgerschen Arithmetik Verwandte Systeme}, journal = {Mathematical Logic Quarterly} }