Worlock used to say these worked great (albeit on the expensive side comparitive to other sources) but I never tried them myself.
Check Worlocks pages at Rhodiums.
https://www.thevespiary.org/rhodium/Rhodium/worlock/toc.html (https://www.thevespiary.org/rhodium/Rhodium/worlock/toc.html)
they still appear frequently at auction sites