The *dating of Primus instructions, pre-1964 (pre-Optimus take-over) *specifically what we here often refer to as printer's date code. shagratork /Trevor RIP posted similarly re The Dating of Svea Documents That was inspired by Sievert Svea 123 dating. The following we can limit to Primus 71 (1/3 pint and 1/2 pint) stoves... IF we might possibly solve those. The printing company Boktryckerf noted below is Ernst Westerbergs Boktryckerf A.-B of Stockholm. Unlike Trevor I do not have suggestion as to how to interpret. I dont comprehend it and I am without suggestion. As i scratch my head (w/limited time), sadly, I post only to share another stovie "...riddle wrapped in a mystery inside an enigma; but perhaps there is a key." 1951 esp has me stumped tofta 1937 tank not stamped. came w/ '37 shorty P71 w/printer's code... Westerbergs Boktr., A.-B Stockholm. Printed in Sweden 15,000 4. 37. -600. source: Primus No 71, 1937, Directions for use 1/3 pt Boktr. abbreviation for ...Boktryckerf... OMC 1938 AC. came with '38 P71 this printer's info: Ernst Westerbergs Boktryckerf A.-B of Stockholm Sweden. 1938. '38 having high level of confidence in complete EUC source: 1938 (AC) Primus 71 (new) 1/2 pint w/pin, (new) dome filler cap, w/(new)air restrictor and (new) vaporizer S Molson 1947 AL. came with '47 P71 this printer's code ...Boktryckerf... 1947. 1762. source: 1947 (AL) Primus 71 L | Classic Camp Stoves 1/2 pint w/pin, dome filler cap, w/air restrictor Wim 1947 AL. P71 instructions with this printer's code ...Boktryckerf... 1947. 3057. source: 1947 PRIMUS N° 71 instructions Pharael 1951 AP. came with '51 P71 this printer's code ...Boktryckerf... 512. 52. 3. '51 having high level of confidence in complete NOS source: Primus No. 71L (1951) - unfired NOS complete in box. 1/2 pint w/pin, dome filler cap, no air restrictor Trojandog 1951 AP. came w/ '51 P71 this printer's code ...Boktryckerf... 59. 52. 1. source Instructions 1951 Primus 71L 1/2 pint w/pin, dome filler cap, no air restrictor night_owl 1951 AP. came w/ '51 P71 this printer's code ...Boktryckerf... 1951. 83. source: Primus 71 instructions (1951, air restrictor) 1/3 pt not shown (pin? vs SRV filler?), w/air restrictor Harder 1956 AV. came w/ '56 P71 this printer's code ...Boktryckerf... 899 5. 56. '56 having high level of confidence in complete NOS source: 1956 Primus 71 (unused) Rodger Willows 1956 AV. came w/ '56 P71 this printer's code ...Boktryckerf... 899 5. 56. '56 having high level of confidence in complete in-box source: Primus 71L (1956) Sedgman 1959 . P71 instructions with this printer's code ...Boktryckerf... 2602. 11. 59. OMC 1961 . P71 instructions with this printer's code ...Boktryckerf... 4901. 4. 61. source: AB BAHCO Primus 71 instruction, 4901.4.61