This July 1953 Electronics magazine features a Type 514 oscilloscope on the cover.

 

This August 1954 Electronics magazine features a Type 524D oscilloscope on the cover.

 

This March 1955 issue of Electronics features a Type 511A oscilloscope on the cover.

 

This April 25, 1958 issue of Electronics features a Type 512 oscilloscope on the cover.

 

This March 1961 issue of Electronics World features a Type 531 oscilloscope on the cover. It is 1957 or later since it has rounded corners. The plug-in is a Type 53A.