Title : The World Environment Day's evidence of booklet's existance.
"Fig.2" from the August 1999's Korean Philately-
Collector Booklet #1568 

In an article by Taizo Maeda, in Korean Philately August 1999; Mr. Maeda says that the first "Collector Booklet" (he calls them "make-shift booklets"), was the "International Rotary Convention issue", of May 20, 1989. That is MIC# 1565; KPC# C1189; MICHEL# 1589; SG# 1868; and Sc# 1534.

Also, the article pictured an example of the June 5,1989 issue "The World Environment Day"; MIC# 1568; KPC#C1192; MICHEL# 1592; SG# 1871; and Sc# 1537.