Houkoku Aircraft Postcards And Photos

I am a Historian/Researcher with a focus on Houkoku aircraft. I am seeking postcards and photos of these aircraft, particularly those for Reisen aircraft. Are there any persons on this forum who collect these, or who are also doing historical research on these? Does anyone have suggestions on where I can find this type of information?
Thanks,
Ed

Here's a list of Hōkokugō. According to this site, a researcher 窶ｰﾂ｡ﾋ?､窶吮?ｰﾂ俊[Yokoi Tadatoshi] wrote a detailed report about Hōkokugō in a magazine ﾂ航窶ｹﾃｳﾂ湘ｮ窶｢ﾃｱ[Kōkūjōhō] '84-2, 3 and 12.

No.1~999
ﾅ?Cﾅ坦窶｢ﾃｱﾂ坂?伉坂??ﾅ陳｣窶拏窶ｹ@窶卍ｲﾂ債ｸﾂ（1ﾂ〜999ﾂ）

No.1000~
ﾅ?Cﾅ坦窶｢ﾃｱﾂ坂?伉坂??ﾅ陳｣窶拏窶ｹ@窶卍ｲﾂ債ｸﾂ（1000ﾂ〜ﾂ）

Also, as you might have already tried, Google have some pictures.
窶｢ﾃｱﾂ坂?伉坂?? ﾅ?G窶杯ﾂ鞘? - Google ﾅ椎ｸﾂ催ｵ