Months and years represent the timestamps on the slides.
1950s-60s (mostly)
1967 (August)
1967: Lithuania (gifted/purchased slides, unknown source)
1968 (February, April, June, November)
1969 (May, December)
1970 (January, April, June, August)
1977: Lithaunia with Ugi
1971: Germany, Italy & Croatia (September)
1976: Paris & Lourdes (September)
1982: Paris & Lourdes (July)