The Key to Success

 is a Quest in Escape from Tarkov.

Dialogue
"Good day to you! We already went so far together, you’re like a brother to me. Like family, see, don’t get me wrong. So, like a brother, answer frankly, do you like reading? I devoured books back then, as a kid. But now I need a serious book, for business. A rare bitch for sure, but I know you can get a devil from under the ground if you'd want. Get me the book about designing clothes from special fabrics, all that military stuff has to be made with aramid fabric, which has its own tricks to it. There should be a manual for them, in two volumes. If you can get it, that’d be capital. Should probably check in the book stores, they must be there."

Requirements

 * Must be level 26 to start this quest.

Objectives

 * Obtain the Clothes design handbook - Part 1 on Interchange
 * Hand over the Clothes design handbook - Part 1 to Ragman
 * Obtain the Clothes design handbook - Part 2 on Interchange
 * Hand over the Clothes design handbook - Part 2 to Ragman

Rewards

 * +15,600 EXP
 * Ragman Rep +0.03
 * 60,000 Roubles
 * 63,000 Roubles with Intelligence Center Level 1
 * 69,000 Roubles with Intelligence Center Level 2

"You really found them? Thank you, friend. Don't get any ideas, these books are very important, they'll help me with my business."
 * 2× Ghost balaclava
 * Unlocks purchase of Eberlestock G2 Gunslinger II backpack (Dry Earth) at Ragman LL3

Guide
The first book is located in a store called "МУЗЕЙ ИСТОРИИ" ("Museum of History") on the second floor of the shopping mall on Interchange. It can be found in a pile of books on the floor. 

La clé du succès Секрет успеха Der Schlüssel zum Erfolg