1. Two new astigmatic charts Author(s): Verhoeff, F. H. (Frederick Herman), 1874-1968, author Publication: Chicago : Ophthalmic record, 1899 Subject(s): Astigmatism -- diagnosisVision Tests -- instrumentation
2. An improved astigmatic chart Author(s): Wallace, James, 1854- author Publication: [Philadelphia?] : [publisher not identified], [1889?] Subject(s): Astigmatism -- diagnosisVision Tests -- instrumentation
