The use of FORTRAN in subroutines with COBOL main programs
Zalman A. Shavell · Communications of the ACM · 1965
By using the proper COBOL coding techniques and accounting for differences in storage allocation and library routines between the two languages, it is possible to write FORTRAN IV subroutines that may be called from COBOL main programs. Such a technique enables the programmer to take advantage of the most useful properties of each language while minimizing their respective disadvantages.