The SFP-MSA spec later renamed to INF-8074i, though the document is the same, part of 4 introductory pages. It contains the mechanical, electrical and ID specifications.

• SFP-MSA Specification
• INF-8074 Specification

The SFP+ spec is named SFF-8431 and sits at revision 4.1 since 2009. It only contains the mechanical, electrical and electrical testing part of the specification. It also refers to other SFF specs, one being the Management Interface for SFP+ as SFF-8472 and contains EEPROM layout (at 0x50) and a diagnostics and monitoring interface (at 0x51), that is read like a dynamic EEPROM.

• SFF-8431 SFP+ MSA Specification
• SFF-8472 Management Interface Specification
• SFF-8024 SFF Module Management Reference Code Tables Specification
• SFF-8079 SFP Rate and Application Selection Specification
• SFF-8071 SFP+ 1x 0.8mm Card Edge Connector Specification
• SFF-8083 0.8mm Card Edge Connector for 8/10 Gbs Applications Specification
• SFF-8461 SFP+ Active Cable Specification and Alternate Test Methods Specification

https://www.snia.org/sff/specifications2 for all specs, requires login!