This firm produced perfins from 1895 to 1897.
Here is a Heymann Sucesores cover produced in that time:
Used 18 August 1897 from Mazatlan to New York City
"H.S." perfin on 2 and 3 centavos Letter Carrier stamps (1895) - Scott 243 and 244
Here are some of the stamps which have H.S. perfins:
Building attributed to Heymann Sucesores.