@article{700889,
     title = {Concerning a categorial approach to topological and algebraic theories},
     booktitle = {General Topology and its Relations to Modern Analysis and Algebra},
     series = {GDML\_Books},
     publisher = {Academia Publishing House of the Czechoslovak Academy of Sciences},
     address = {Praha},
     year = {1967},
     pages = {176-181},
     mrnumber = {MR0230784},
     zbl = {0184.25803},
     url = {http://dml.mathdoc.fr/item/700889}
}

Hedrlín, Z.; Pultr, A.; Trnková, V. Concerning a categorial approach to topological and algebraic theories, dans General Topology and its Relations to Modern Analysis and Algebra, GDML_Books,  (1967), pp. 176-181. http://gdmltest.u-ga.fr/item/700889/