ENGLISH ALPHABET
26 letters · 5 vowels · 21 consonants
$1.50
GREEK ALPHABET
24 letters · names and where science uses them
$1.50
MORSE CODE
26 letters and 10 digits · dot, dash
Free
PHONETIC ALPHABET
the ICAO standard · for radio and telephone
$2.50
SI PREFIXES
from quetta to quecto · twenty multipliers
$1.50