The last two equations were given (

The last two equations were given (though with different notations) by .
Winberg (1956), who also gave a rough estimate for pl es 0.8.
By replacing the symbols in these equations with actual values obtained
for pond fishes, it should be possible to determine their requirement for
food energy. Some attempts have been made at estimating these values for
various fish species. Table 3 gives, for example, some estimates of (pt) These
seem to support Winberg's rough estimate, and indeed, the equations and “