"Lubricating 10 Billion Miles"
1929
"Speeding the flow of Texaco to 12,000 cities"
1930
I've only seen this jpeg, it's either a Dunn or a Saul Tepper. It is signed. Does anyone have a better scan? (please upload and link)
""Covered Wagons" of 1930"
1930
attributed
"Trails No Map Will Ever Show"
1930
"Research the Guide to Progress"
1930
"Does Winter Strike Terror…?"
1930