NL fundamental

[malokoman]

Hello all, long time reader first time poster. In the past i've been strictly a limit player. Lately i've been studying different games ( O8, stud hl) and would like to learn more about NL with regards to fundamentals. I've already learned a great deal by just reading archives but so far have been unsuccessful in finding posts on suggestions of books that may be of help. Are there any principle books out there such as TOP and HEFAP aimed at NL? From what i've heard many books out there on NL are bogus, so I would like to avoid them. Thanks everyone in advance as I look forward to posting more and improving my game through this great site.