Abbreviation of "continued"

As a student (many years ago), I was taught that cont'd was the proper abbreviation for continued. However, today I aslo find sources that say cont, con't, and contd are acceptable abbreviations for general writing.

Given this range of answers, I turned to the bible used by my profession -- ANSI/CSI TD-24. -- and related standards -- ANSI/ASME Y14 and ANSI/AISC Code of Standard Practice. In the previous sentence, ANSI = American National Standards Institute, CSI = Construction Specification Institute, ASME = American Society of Mechanical Engineers, and AISC = American Institute of Steel Construction.

These sources agree on the following:

• If at all possible, avoid abbreviations. (This agrees with the style manual advice for formal writing.)
• Abbreviations should not include punctuation. This means no periods or apostrophes. (This contradict most grammar and style advice.)
• Continued = contd
• Continuous = cont

I hope this helps.