Reference to formula

[Leon Gerber]

I'm looking for a reference(s) to a formula that is used to calculate the
corrected WBC (cWBC) with regard to the nucleated RBC count (nRBCc):

    cWBC = (total WBC * 100) / (nRBCc + 100)

Used for example in Coulter Counters when doing blood counts.

Thanks
Eljay