Kazem Taghva. Model completeness and direct power. Math. Log. Q., 36(1):3-9, 1990. [doi]
@article{Taghva90, title = {Model completeness and direct power}, author = {Kazem Taghva}, year = {1990}, doi = {10.1002/malq.19900360102}, url = {http://dx.doi.org/10.1002/malq.19900360102}, researchr = {https://researchr.org/publication/Taghva90}, cites = {0}, citedby = {0}, journal = {Math. Log. Q.}, volume = {36}, number = {1}, pages = {3-9}, }