Nulls in cited patents
The uspto (and hence patentsview) has full data for patents issued in 1976 and above. Only a handful of fields are available for pre 1976 patents at uspto.gov (issue date, uspcs, cpcs and obviously patent number). The reference table below is copied from uspto.gov for patent D756514
If you compare the reference table to the patentsview data for that patent you'll see that the nulls returned by patentsview correspond to the pre 1976 patents referenced. It makes sense that the titles wouldn't come back but at a minimum I think the patent number should be returned.
|Patents Cited in D756514|
|3247324||April 1966||Cefaly et al.|
|3618697||November 1971||Littmann et al.|
|6883639||April 2005||Lam et al.|
Data returned by patentsview