contents: add links to company preparation PDFs

contents/companies/amazon-front-end-interview-questions.md

@@ -3,7 +3,7 @@ title: Amazon front end interview questions
 sidebar_label: Amazon interview questions
 ---
 
-Amazon is known to focus a lot on behavioral questions and their Leadership Principles. Hence be well-prepared in the non-technical aspects too.
+Amazon is known to focus a lot on behavioral questions and their Leadership Principles. Hence be well-prepared in the non-technical aspects too. Refer to the [official Amazon Interview Preparation Guide for Software Development Engineer](https://amazonsdeinterviewprep.splashthat.com/).
 
 ## Trivia
 

contents/companies/dropbox-front-end-interview-questions.md

@@ -3,6 +3,12 @@ title: Dropbox front end interview questions
 sidebar_label: Dropbox interview questions
 ---
 
+Dropbox focuses on practical questions for their Front End Engineering interview loop rather than on raw algorithmic coding.
+
+> Our web developer interviews focus on practical application of HTML/CSS/JS for building web UI. The questions are based on real-world examples rather than raw coding exercises. You will be given a design spec and asked to build the best solution you can that demonstrates your experience and grasp of web development technologies.
+
+Refer to the [full official Dropbox Web Developer Interview Preparation Guide](/companies/dropbox.pdf).
+
 ## JavaScript
 
 - Implement [`getByClassName()` and `getByClassnameHierarchy()`](https://leetcode.com/discuss/interview-question/427896/Dropbox-or-Phone-Screen-or-Implement-getByClassName-and-getByClassnameHierarchy)

contents/companies/google-front-end-interview-questions.md

@@ -5,6 +5,10 @@ sidebar_label: Google interview questions
 
 Since it's Google, candidates can expect to be tested on fundamental Computer Science concepts as well as their front end knowledge/skills.
 
+> Web Front End: ​You should be ready to cover topics like front end latency and implementation of standard CS algorithms using idiomatic JavaScript. You should be able to articulate Javascript strengths and shortcomings and ready to cover any of the following: Web security issues (XSS, XSRF), Prototypal inheritance, DOM API & manipulation, CSS manipulation, Browser / DOM events & event handling, XHR requests & HTTP headers, JavaScript closures
+
+Refer to the [full official Google Interview Preparation Guide for Front End Software Engineer](/companies/google.pdf).
+
 ## JavaScript
 
 - Implement the outline view for a Google doc.