Development of an APL standard. - Adin D. Falkoff; Donald L. Orth (APL, 1979)

A comparison of the IPSA and STSC implementations of operators and general arrays. - Donald L. Orth (ACM SIGAPL APL Quote Quad, 1981)

Empty Arrays in Extended APL. - Donald L. Orth (IBM J. Res. Dev., 1984)

Compiling APL: The Yorktown APL Translator. - Graham C. Driscoll Jr.; Donald L. Orth (IBM J. Res. Dev., 1986)

APL-compilation - where does the time come from? - Graham C. Driscoll Jr.; Donald L. Orth (APL, 1987)

Indexing and Merging in APL. - John A. Gerth; Donald L. Orth (APL, 1988)