From booklet:

Instructions are for size Small. Changes for Medium and Large are in parentheses.

MATERIALS - Sport Yarn Weight

SPINNERIN Sabrina (50-g) Bikini 3(3-4) Cover-up 10 (12-14)
OR Elf (1-oz) Bikini 6(6-7) Cover-up 20 (24-28)

CROCHET HOOK: “Boye or Diana” Size F and G OR SIZE TO GIVE GAUGE

1 pkg round elastic; 4(4-5) pkg plastic rings 5/8 inch in diameter; 4 buttons

GAUGE: Bikini 6 sts = 1 inch; 5 rows = 1 inch
Cover-up 5 sts = 1 inch; 4 rows = 1 inch

FINISHED MEASUREMENTS (in inches)
Bikini -- Bust 32(36-40)
Hips 34(38-42)
Cover-up Bust 34(38-42)