Performance Monitor

PerfMon Objects, Counters, Thresholds, & Utilities for SQL Server 
by Jimmy May

[older article, still relevant, includes an Excel file to download - lots of info]

http://blogs.msdn.com/b/jimmymay/archive/2008/10/15/perfmon-objects-counters-thresholds-utilities-for-sql-server.aspx



Additional books that might be of interest:

Microsoft SQL Server 2012 Internals
Kalen Delaney, Bob Beauchemin, Conor Cunningham, Jonathan Kehayias, Paul Randal, Benjamin Navarez

[If you want to get more into the basics and how things work, this is a great reference.]

http://www.amazon.com/Microsoft-Server-Internals-Developer-Reference/dp/0735658560/ref=sr_1_1?ie=UTF8&qid=1447898876&sr=8-1&keywords=sql+server+internals


Microsoft SQL Server T-SQL Fundamentals (Third Edition)
Itzik Ben-Gan

[Good start for T-SQL]

https://www.amazon.com/T-SQL-Fundamentals-3rd-Itzik-Ben-Gan/dp/150930200X/ref=sr_1_1?ie=UTF8&qid=1493312037&sr=8-1&keywords=t-sql+3rd+edition+itzik

T-SQL Querying
Itzik Ben-Gan and Adam Machanic

[Next steps for T-SQL]

http://www.amazon.com/T-SQL-Querying-Developer-Reference-Ben-Gan/dp/0735685045/ref=sr_1_5?ie=UTF8&qid=1447898943&sr=8-5&keywords=sql+server+tsql+query
