I’ve always been fascinated by social customs and business etiquette, and MBA schools are now teaching young professionals proper manners. Business etiquette changes over time!
In the early 19th century it was proper to pour tea into your saucer and slurp it directly, and then wipe your lips on the tablecloth!
Picking a good source is business etiquette is important, stick with American etiquette, oif you want good manners:
Pick an American source for proper etiquette
My young MBA’s don’t learn important business etiquette in MBA schools these days, and they often commit a faux paux like choosing a funky wine for dinner:
Don’t choose a wine just because it has a high tech name
All business professionals should learn business golf etiquette, as many business meetings are conducted on the golf links these days.
See my notes here on business etiquette for professionals