I am having trouble with determining the gender of de-words. I know that the Dutch masculine and feminine have basically merged but the distinction is still made in the pronouns that refer to them, so it is important. I am having trouble with finding out if words that do not have the recognizable suffixes such as -heid and -nis are feminine (and any other suffixes and patterns, such as nouns that are derived with just the stem and occasionally a vowel change being mostly masculine). Mostly it is the one-syllable words which don't consist of anything but a root that present a problem. The dictionaries I have found online have "v/m" written next to them, which is rather obvious, since it is a de-word. I was having trouble with "stip" and "buis" recently.
How can I know if any such words they are feminine or not? If it is completely random, could someone suggest a dictionary online where it is specifically stated whether the noun in question is feminine or masculine?